Chicago's food scene, including vegetarian options, has taken off in the past decade, making it arguably the second-best restaurant city in the U.S.A.  If you want the best and are prepared to pay, you can have a truly great dining experience in Chicago.

Best of the Best

Alinea
Alinea is the hottest table in Chicago, and for good reason. In his small Lincoln Park restaurant-laboratory, wunderkind Grant Achatz presents unexpected dishes in unexpected ways.  Achatz, who has studied with both Ferran Adria and Thomas Keller, is perhaps the country's foremost chef of molecular cuisine, taking delight in deconstructing the way we eat--a dish may be a plate of venison served on a pillow of lavender-scented air (so that the scent wafts up as you eat) or bacon strung on a wire.  The restaurant itself is chic and neutral, and service is polished but cool.   Nothing is a la carte--you choose between two chef's menus--a 12 course "tasting" menu at $145 or a 20 course "tour" at $225.
Charlie Trotter's
Foodies still flock to the flagship restaurant of Charlie Trotter, the man who put Chicago on the map as a food destination.  The restaurant, in Chicago's Lincoln Park neighborhood, has a traditional, quiet feel, but as you'd expect, Trotter's creativity shines in the two tasting menus:  the vegetable menu ($135) or grand degustation ($155).  Trotter's dishes reveal both the chef's addiction to perfection and his dedication to organic and free-range, locally sourced ingredients. While the menu changes constantly, expect such delights as whole roasted squab breast with birch, black trumpet mushrooms & devil’s club or candied Buddha’s Hand with lemon, ricotta & taggiasca olives.  Trotters is also justly famous for its exquisite, gracious service.   If you're with a group and want a truly memorable experience, you may try to score reservations to the Kitchen Table (about $250), where, as the name suggests, you will be seated in the kitchen itself, with a dedicated server who will explain the workings of the restaurant to you while you dine on your unique menu.  

Everest

Spiaggia

Topolobampo

Less Famous but Fabulous

If you don't have the pocketbook for Alinea, try one of the following group of restaurants.  While they may not have the reputation of a celebrity chef behind them, each is highly acclaimed and definitely worth a trip on a special night.

Blackbird
Blackbird may have the ambience of a crowded bistro, but come here for the spectacular food (and great people-watching).  The creative, artful menu change seasonally, and Chef Kahan includes dishes such as roasted walleye with coco beans, celery pistou, cured plums, coconut and lavender candied walnuts.  The small, largely blank space gets very noisy on weekends and is packed with tables--you'll be impressed just watching your server weave deftly through the maze of tables.  Entrees average about $30; be prepared to spend about $75 a person, plus drinks and tip.

L2o
L2o, widely considered the best new Chicago restaurant of 2008, specializes in exquisitely prepared seafood. The hushed, neutral decor, unobtrusive service, and chic patrons give the experience a distinctly modern feel.  The menu changes constantly, but includes such dishes as raw salmon with ginger and cantelope and peekytoe crab with keffir lime.  You may order a la carte, but consider trying L2o's four or twelve course tasting menus.  An evening at L2o will set you back between $125 and $175 per person, not including drinks or tip.  For a special evening, consider reserving their private tatami rooms for two.

moto
If you crave mad-scientist levels of experimentation, Homaro Cantu is your man.  His fabulously creative "molecular cuisine" extends to details such as--yes--edible menus and dishes that toy with your expectations (one dessert appears to be a hotdog, complete with relish, but is actually sorbet and pound cake with a minted sauce).  Dishes may be "cooked" tableside with liquid nitrogen.  The cost of such cutting-edge cuisine?  Your choice of a 10-course tasting menu at $115 or a 20-course menu for $175.

North Pond
Nestled by a small lake in Chicago's Lincoln Park, the lovely Arts and Crafts cottage of North Pond may have the most romantic setting of any restaurant in Chicago.  The cuisine emphasizes artful presentations of perfectly prepared local ingredients--you may find yourself marveling at how something that appears so simple can taste quite so good.  Entrees, which include such delights as sage-basted breast of pheasant with red wine cabbage, gratinéed bacon-almond farro, and foie gras sauce, average about $35.

Spring
Chicago fixture Shawn McClaine's Spring is a long-time local favorite.   The menu

Tru

For Romantics

Lovers may enjoy Geja's Cafe, which although not what most would consider fine dining bills itself as "the most romantic restaurant" in Chicago. Service is attentive and discreet.  The restaurant, set below ground level, is dimly lit and decorated with a Spanish/Moroccan feel.  The tables are small and cozy, some booths separated from others by overhanging red velvet drapes--for the most romantic evening, ask for a private booth.  Geja's features live flamenco nightly.  A typical four-course meal (which will include a main course, fruits to dip in the melted cheese, marshmallows to roast, and, of course, strawberries in melted chocolate) costs between $75 - $100 per person, not including drinks.