ORLANDO, Fla. -- Architect Sarah Susanka's 1998 book "The Not So Big House" launched a revolution that in many ways redefined the new American home. Captivated by her "build better, not bigger" philosophy of home design, builders have focused on smaller, more environmentally responsible homes where quality reigns supreme. But in sunny central Florida, the sprawling McMansion is still king, if two of the show homes at last week's International Builders Show are any indication.

The New American Home 2008 is a 6,725-square-foot, two-story monster. Get past its two-story formal living room, paneled library and second chef's kitchen with dual islands and you've still got 2,950 square feet of covered outdoor space, including a dining area with full kitchen, adjoining "solona" with gas fireplace and a screened loggia that overlooks a salt-water pool and Jacuzzi. Its equally mammoth asking price: $4.8 million.

Bigger still and even more outrageously lavish is the New Southern Home on the northern shore of nearby Lake Anderson. This six-bedroom stunner, which was built last summer for the 29th annual Southeast Building Conference, boasts a whopping 18,200 square feet under roof, 12,200 of it air-conditioned. Its amenities include a billiards room with full kitchen, craft room, library, home theater, 11 baths (eight full, three half) and -- whew! -- a cabana off the pool with summer kitchen. There's also an attached carriage house with a one-bedroom apartment and a porte-cochere for dropping off groceries before pulling your car into one of three garages.

This year's 25th anniversary New American Home is not the largest in IBS history; that honor goes to the 10,023-square-foot 2006 show house in Windermere, Fla. But both are a far cry from the first one, a 1,500-square-footer built for a mere $80,000 way back in 1984. Then again, the average American home has more than doubled over the past half-century, swelling from just 983 square feet in 1950 to 2,434 square feet in 2005.

Show homes are meant to knock viewers' socks off by showcasing what's possible when money is no object. And this plantation-style residence, one of 11 planned homes in the exclusive Water's Edge gated community 10 miles north of the city, will have you barefoot quicker than most. Builder Charlie Robertson of Robertson Homes spared no expense in creating an opulent but still livable house for the ultra rich. He's guessing it will sell to a professional athlete (golfers Ernie Els and Sergio Garcia live in the private golf community across Lake Nona) or maybe a doctor from one of the region's many medical facilities.

Mr. Robertson says he was inspired by the devastation of Hurricane Katrina and all of the historical homes that were destroyed. And to be sure, this stately white stucco home, with its soaring columned portico, wrought-iron balconies and tall windows that let in light and breezes, evokes the antebellum country manor homes of the deep South.

As a symbol for the cutting edge in home design and building products, however, it's also loaded with the latest in technology and -- in a nod to the green building movement -- sustainable materials. It's the first show home to be certified by the National Association of Home Builders new Green Building Standards.

One of the home's more innovative features is a pair of remote-controlled, full-height sliding glass doors in the 25-by-30-foot family room. Touch a button and they open to the pool area, bringing the outdoors in. It is also wired inside and out for sound (speakers are hidden in the walls or flush-mounted on the ceiling so they don't detract from the decor) and equipped with an "intelligent" lighting system, which allows the homeowner to turn lights on or off on a pre-set schedule and create lighting "scenes" for particular activities. Other high-tech touches include programmable shower heads, a solar hot water heater and retractable "phantom" screens in the back porch area that are so fine-meshed they're practically transparent.

What's most striking, however, is the home's architectural details. Dan Sater, principal of the Sater Group in Bonita Springs, Fla., designed the interior so it's flush with trim work and double- and triple-crown moldings. Most rooms also feature a unique ceiling treatment -- there's a cypress radial design in the family room and a flower-like coffered ceiling in the formal dining room. The balconied grand salon, meanwhile, has paneled walls and silk-draped windows that stretch a full two stories, offering not just a view of the pool but also of the lake beyond. All other rooms have 12-foot ceilings.

The gourmet L-shaped kitchen, obviously designed with entertaining in mind, wows with two separate islands (one for food prep, the other for snacking), oiled bronze appliances and furniture-like Timberlake cabinetry in two finishes: cognac and butterscotch-glazed maple. A "baking center" includes two wall ovens and a warming drawer, and there's also a butler's pantry with an icemaker and under-counter wine cooler for the caterer.

The first-floor master suite takes up an entire wing of the first floor and includes both a walk-in closet with an entire wall of cabinets (there's even one for your ties and belts), a luxurious bath with his-and-her vanities, a walk-in shower with glass-tile inserts and pebbled floors, and a giant circular whirlpool tub. Adding to the room's tranquility is a floor-to-ceiling tiled water feature.

The second floor contains two guest rooms with balconies and a laundry/craft room with stackable appliances. A high-tech media room/game room boasts a wet bar and gas fireplace and opens through French doors onto a sundeck overlooking the pool. The hall is open to both the foyer, where a wine cellar is tucked beneath the staircase, and the grand salon.

Following the trend toward multi-generational living, the house includes a spacious "bounce back" suite for aging parents and boomerang adult children. There's also a "family valet" area off a secondary entrance with a built-in locker for shopping bags and sporting gear, and a flip-open charging station for iPods, cell phones and laptops.

The shingle-style New Southern Home, meanwhile, is even bigger, with 22-plus rooms. Yet its open floor plan and many large windows give it a light and airy feel. The eat-in kitchen, which features light-colored granite countertops and twin islands, is especially bright, unless you count the adjacent safe room with titanium locks. Just as awe-inspiring is the master bath's cave-like walk-in shower. Roomy enough for an entire family, it's larger than many kids' bedrooms. Then again, this house sells for more than $5 million.

Other wish-I-had-that touches include SmartLabs' INSTEON lighting control system, which allows homeowners to remotely turn on or off all lights in a house and change their intensity; several wine and beverage bars, because in a house this large you're probably pretty far from the kitchen; a workshop with acid-stained concrete floors; and a hot tub off the covered lanai that feeds into an infinity swimming pool.

Maybe bigger really is better.