The brown bag lunch is one of the most visible examples of Americans' new frugal habits. But people miss out on more than extra calories and table service when they eat lunch in the office.

Think of a restaurant lunch as a midday mini-vacation, yielding amazing powers of rejuvenation. Lunch also gives diners a chance to try top-notch restaurants at often significant discounts.

Noon is prime time in Downtown Pittsburgh, so don't even think about having a European late lunch at 3 p.m. (something that restaurants might want to reconsider while the G-20 is taking place). Lunch pacing also can be surprisingly leisurely, so if you're shooting for three courses in an hour, let your server know.

Here are several Downtown dining options I'd recommend for a delicious, luxurious lunch.

With its gleaming wood floors, lush flower arrangements and silk draperies in grays and blues, Nine on Nine is elegant and opulent even at lunch, when the rarefied atmosphere is taken down a notch. Butcher paper covers the white tablecloths and the menu is more casual, with sandwiches and salads alongside more substantial main courses. But you'll get the same quality of ingredients and impeccable preparations at lunch as well as at dinner. Service is attentive and discreet.

Chilled pea soup ($6) is the soup of the season, appearing on a number of menus around Pittsburgh, and this version is spectacular. The sweet, green pea puree could stand alone, but it's augmented and enriched by smoked mussels, lemon creme fraiche and pickled whole peas.

The rich, gamey flavors of chicken liver pate topped with a glistening layer of aspic will transport you straight to a Parisian bistro. A large ceramic dish of pate ($8) is accompanied by buttered, crispy toast points, whole grain mustard, cornichons and a pile of house-made pickles: Cauliflower, carrot and celery.

For a taste of the New England shore, don't miss the soft-shell crab sandwich ($12). Few kitchens turn out such perfect specimens of this seasonal delicacy, the thin shell rendered crackly-crisp.

Seared tuna may be the most expensive ingredient in Asian tuna salad ($14) -- and it was delicious, more flavorful than a lot of tuna these days -- but the most impressive components of the dish were the perfectly cooked soba noodles, with their nutty, almost sour flavor, and the masterful combination of slightly bitter mixed greens and a savory-sweet miso-mustard dressing.

Avoid the office vending machines for the week and order dessert here instead. The doughnut-like fritters, served with berry, honey-yogurt and white chocolate-basil sauce (the table's favorite), were perfect for sharing ($8).

The Terrace Room at the Omni William Penn has recently been refurbished, balancing the old-fashioned grandeur of its chandeliers and murals with a subtly patterned carpet and eye-catching, jewel-toned booths and armchairs. While hotel dining rooms often disappoint, the Terrace Room is an oasis where the quality of the food lives up to the glittering setting. The menu offers American classics such as Cobb salad ($14) and a black Angus burger ($13) alongside dishes showcasing French- and Italian-inspired techniques and flavors.

The inevitable chicken dish is rarely a standout option on a menu, but the chicken paillard with linguini and nightshade Terrace sauce ($19) is remarkably memorable. The thinly sliced pieces of breast meat were lightly breaded and sauteed with impressive care, resulting in an ideal contrast between crunchy skin and moist meat. The sauce, a play on the fact that tomatoes are part of the nightshade family, turned out to be a flavorful marinara made from cherry tomatoes, cooked until they softened and released their juices.

It seems that after so many years of tuna tartars, restaurants once again feel free to return tuna to the entree portion of the menu. At the Terrace Room, a generously sized tuna steak has a refreshingly Mediterranean flavor profile, its meaty flavors well-matched by a chunky tapenade and crunchy fennel slaw ($14).

The best of the desserts was a trio of creme brulee ($8), made special by a particularly elegant style of service. A long thin plate became a frame for three colorful splotches of bronzed sugar -- three indentations filled with shallow pools of butterscotch, chocolate and vanilla custard.

When the Capital Grille opened, people expressed reservations about whether the Downtown economy could support another expensive steak house. Almost two years later, it's found its niche, attracting a steady crowd of regulars as well as special occasion diners with its classic mahogany and linen decor, traditional service, dry-aged steaks and bold cabernets.

It might seem sacrilegious to order a salad for lunch at such a restaurant, but the chopped salad with citrus-grilled shrimp ($17), garnished with just the right amounts of asparagus, cherry tomatoes, cucumber and corn, packs such bright, summery flavor into each bite that this light lunch is impressively satisfying.

For those who love steak houses for the meat, you can't do much better than the herb-marinated, dry-aged sirloin served with sweet roasted red peppers and cipollini onions ($29).

Large servings and comfy chairs can make it hard enough to leave the Capital Grille and head back to the office, but diners who take advantage of a special wine-tasting opportunity this summer may need to take the rest of the afternoon off.

Just let your server know you'd like to take part in the Master Wine Tasting event ($10 at lunch, $25 at dinner) and you'll be poured generous tastes of a dozen different wines selected by the Capital Grille's master Sommelier George Miliotes.

From Monday to Aug. 2 the Master Wine Tasting Event wines will include top bottles from Argentina and Spain. From Aug. 3 to Aug. 23 selections will be from South Africa and the Napa Valley. Servers will make pairing suggestions and guide each diner through the tasting.

We can't all live Downtown in luxury condos with views of the river, but a lunchtime escape to one of these restaurants is an excellent way to get a taste of all that this city has to offer.