WHY GET THE HO-HUM

cup of plain coffee when you can get a nonfat caff mocha with an extra shot of espresso and whipped cream? You can trade up for practically anything these days, from that morning cup of java to the gas in your car's tank.

Sometimes the decision to trade up is obvious Godiva chocolates instead of Russell Stover? Yes, please! But in most cases, the decision to upgrade your purchase isn't so cut and dried. It's as much about our perceptions as what we actually get, says Michael J. Silverstein, senior vice president for Boston Consulting Group and author of "Trading Up." "If you buy a Victoria's Secret bra and panty set, you are getting sexy and glamorous," he says. "If you drink Belvedere vodka, you are demonstrating taste and sophistication."

We can't tell you if you'll feel more like a gourmand for having purchased a $3,500 GE Convection Oven. But whether you want a better airline seat or a bigger diamond, here's what you're getting (and what it's worth) when you trade up:

Airfare

What you'll get: No matter which airline you're traveling on, forgoing coach for business or first class comes with one major advantage space. Most domestic and international economy seats have 29 to 33 inches of leg room (measured as the distance between two rows of seatbacks), according to SeatGuru.com, a site devoted to airline seat information. Trading up gives you a wider seat, plus another five to seven inches of leg room in domestic first class. In international business and first class, you'll get another 30 to 60 inches of leg room. If moving beyond the reach of seat-kickers isn't enough incentive, there are plenty of other airline-specific perks. A first-class ticket on Virgin Atlantic, for example, includes transportation to and from the airport, a pass to the airport Clubhouse lounge and in-flight spa services. On American Airlines, business and first-class passengers receive an aromatherapy amenity kit, and have access to noise-canceling headphones and a laptop power connection.

Making the trade: "Upgrade whenever you have the cash," says George Hobica, publisher of Airfare WatchdogTo locate Y-Ups, check out this guide You may also spot fare sales specifically for business and first class. No luck? If you can't find a way around paying the full fare, save your upgrade dollars for flights of four hours or longer, Hobica advises. It just doesn't make sense to fly first-class for a quick hop from Boston to D.C.

Sample cost: Travel on Continental from Newark, N.J., to Paris on Nov. 20-24, and you'd pay $1,490 roundtrip for a coach seat. But thanks to a sale, a business fare for the same itinerary is $1,350, rather than its typical $3,950.

Appliances

What you'll get: Bells and whistles are the hallmark of deluxe appliances, says Carolyn Forte, homecare director for the Good Housekeeping Institute. Among other technological goodies, a stainless steel KitchenAid built-in dishwasher ($1,449.99 at Sears) has sound insulation to quiet machine noise and specific cycles to eliminate bacteria and remove baked-on food. Often, trading up also means increased energy efficiency, she says.

Making the trade:$1,299 at Home Depot and one that doesn't ($1,099, Home Depot). According to Energy Star estimates, the energy-efficient fridge saves $32 in energy annually; and so would pay off its added cost in a little more than six years. Beyond energy efficiency (and for products like ranges where it isn't an option), take a close look at your needs, suggests Sharon Franke, kitchen-appliances director for the Good Housekeeping Institute. Spending $200 more for convection technology on your range's oven won't be worthwhile if your roasting repertoire is limited to a Thanksgiving turkey. "Having the technology is unlikely to change your cooking habits," she says.

Sample cost: Frigidaire's 3-Cycle Crown Electric Dryer is $199.99 at Best Buy. For $279.99, you can get the brand's 4-Cycle Electric Dryer. In addition to the extra cycle, it offers additional temperature settings, an interior light and a Press Saver function to reduce wrinkles.

Beauty products

What you'll get: Looking for alpha hydroxy acids or retinol? They are easy to find both in the corner drugstore and at your department store beauty counter. But when you upgrade to a department store brand, you'll get higher concentrations of such active ingredients, says L. Bayly Ledes, beauty director for Real Simple magazine. You'll also see more expensive ingredients, such as the fermented sea kelp in celebrity-favored moisturizer Cr me de la Mer ($195 for a two-ounce jar at Neiman Marcus). When you trade up for cosmetics, you're getting more pigments, particularly in bright shades of lipstick and eye shadow. "The colors are much more vivid," says Ledes. Formulas may also add ingredients to make the product longer-lasting (blush), more moisturizing (lipstick), or easily blendable (eyeliner).

Making the trade: The general rule of thumb, says Ledes, is to consider trading up if you're looking for a product to treat a specific issue whether it be limp hair, dry skin or acne. That's when those pricey ingredients and complex formulas are worth their weight in gold. Just looking for a good, all-around moisturizer or shampoo? Hit the drugstore. For cosmetics, you're still getting quality when you trade up, but usually drugstore beauty buys are an equally attractive (and less pricey) option.

Sample cost:$22 at Sephora.

Diamonds

What you'll get: Any guy who's shopped for a ring (not to mention any girl aching for a proposal) can recite the four Cs of diamond buying cut, color, clarity and carat weight from memory. "The better a diamond is, the better it holds its value," says Helena Krodel, spokeswoman for the Jewelry Information Center, a trade association. Increasing carat weight, of course, yields a more sizable diamond. When you trade up for cut, you're getting a stone with more balanced proportions to better reflect light. But upgrading doesn't always mean more: With improved color or clarity in a stone, you're actually getting less. For color, the finest diamonds are colorless, while lower grades may have some yellow tint. Diamonds with a low clarity grade have both interior blemishes and external inclusions; the better the stone, the fewer such flaws.

Making the trade:$25,360 at Diamonds.com and one of similar attributes that is 1.87 carats ($20,596, Diamonds.com) will be in the size of your bank account balance.

Sample cost: At Blue Nile, we spotted a round, one-carat diamond (G color, VS1 clarity) with a "good" cut for $6,223. A stone with the same attributes but a "very good" cut was $6,746; an "ideal" cut $7,102.

Electronics

What you'll get: Trading up in electronics is all about three things: speed, functionality and design. Exactly which depends on the type of electronic device you're buying, says David Carney, executive editor of CNET, an electronics review site. The new BlackBerry Pearl, for example, offers a sleeker, smaller unit with a camera and MP3 player.

Making the trade: "The thing people have to realize is that whatever you buy today will be exceeded," says Carney. "Within a year, there will be a better version." So don't make the trade up simply to have the latest and greatest, or in an attempt to avoid upgrading down the line. Instead, assess your needs, says Carney. A faster processor is a great upgrade if you enjoy computer games, and that large music collection is best compiled on a bigger MP3 player. And the best time to trade up? After a new product is released prices of the older models drop dramatically.

Sample cost: A 2GB iPod Nano is $149. For $50 more, you can get double your player's capacity a 4GB Nano is only $199. There's also an 8GB Nano for $249.

Gas

What you'll get: If you're the type to tout the power under your hood, listen up better grades of gasoline increases horsepower in high-performance engines. Because premium gasoline is also high-octane (meaning it is slower to ignite), it's less likely to cause engine knocking or pinging.

Making the trade: Not every engine will benefit from premium gasoline, says Karl Brauer, editor in chief of Edmunds.com. To figure out what kind of gas you need, check the requirements noted in your owner's manual or on the fuel cover. If it says premium gas is "required," do it putting in regular can damage your engine and even void your warranty. When premium gas is "recommended," you can use either grade. On regular, an engine for which premium is recommended may have slightly less power, says Brauer, but only such that it may take an extra second or two to reach 60 miles per hour. If premium gasoline isn't required or recommended for your car, save your cash.

Sample cost: Texas residents are currently paying about $2.33 per gallon of regular, according to AAA, compared with $2.55 per gallon for premium. Filling up a 2006 Subaru Impreza (the manufacturer recommends premium fuel for the vehicle's 15.9-gallon tank) would cost $37.05 or $40.55, respectively.

Tickets (Concerts, Sports, Theater)

What you'll get: "When you're three rows from the stage, maybe you can touch the palm of the man who wrote your favorite song," says Jennifer Swanson, spokeswoman for Ticketsnow, a ticket marketplace. Trading up for a better ticket is all about the experience those close enough to the action can watch Yankee Derek Jeter sweat, or interact with cast members of Broadway musical "Hairspray" dancing up the aisles. In some cases, upgrading your ticket is the only way to get into coveted, sold-out events like the Super Bowl or Barbra Streisand's last tour.

Making the trade:For more tips on getting great deals, see our columns on tickets for Broadway, sports events and concerts

Potential cost: If you want to assess the Amazin' Mets' chances of beating the Yankees in a Subway Series playoff, a regular season seat in the upper level will cost you $9. Trading up for a reserved seat on the mezzanine is $25; and an inner field box is $50.