great food, fun atmosphere, where to go?

I live in Milwaukee and come down to Chicago once in a while. Am heading down to stay overnight with my husband and two other couples to celebrate a couple of birthdays in early Jan. Don't need a steak place, we've got lots of those up here. Ethnic like asian or caribbean or upscale mexican would work out fine. Type of food is flexible but it has to be excellent. And fun atmosphere would be good too. High quality cocktails are desirable but not required. We are staying just north of downtown. Any recommendations for me?

Sure! All of these are exactly what you're looking for...

pan-Asian:
Red Light (West Loop)
Aria (Loop)

Tapas:
Mercat a la Planxa (South Loop)

Latin fusion:
Nacional 27 (River North)
Carnivale (West Loop)
Cuatro (South Loop)

Mexican:
Frontera Grill and Topolobampo (River North)
Mundial Cocina Mestiza (Pilsen)

(We have many restaurants in these categories, but I consider these the best of each, with an eye towards your desire for a fun atmosphere.)

Though it doesn't appear to get a lot of love from this forum, I keep hearing solid reports on Sunda from friends who are food enthusiasts (though they don't feel the need to discuss it on the internets, heh). Whenever I pass, it looks pretty active and fun, as well. Not really my scene, as I'm not cool/rich enough to party in River North, but when visiting from out of town, its a fun diversion. That'd fit the "Asian" part of your description, although it's certainly not an Argyle- or Wentworth-type place.

You probably don't have Mediterranean in mind when you say "ethnic", but again and again, when I'm looking for good food downtown, I find myself at avec. It's simply a great place to have some food that is fulfilling and familiar, but unique as well. Can't go wrong with whatever pasta they have, as far as I'm concerned. Also great for getting blitzed on some delicious, reasonably-priced wine or beer. Not to mention it's super casual and just fun to be in.

Sunda
110 West Illinois Street
(312) 644-0500

avec
615 West Randolph Street
(312) 258-8331

When considering Avec, there are several things you really need to know. It's small, and they don't take reservations; at peak times, waits of 60-90 minutes are common. They have only communal seating (a bar seats around ten and all the tables are eight-tops), and it's on the most uncomfortable seats you'll find anywhere. Maybe you're willing to overlook all of that for the food; FWIW, I've found the food there overhyped and disappointing, but a lot of other people like it.

The food is some of the best in the city, the vibe is fun, and the cocktails are great at my favorite restaurant and fav of this board, Graham Elliot, just north of downtown in River North.

If you feel like experimenting with someplace brand new (it's less than a week old as I write), Cuna actually matches up with your description pretty well. (The food has no defined ethnicity that I can determine, but it's more adventurous than the steakhouses you want to avoid, and the execution of the food is very good. The atmosphere seems to be shooting for casual fun. The one departure is that if you're staying "just north of downtown," and the place has to be walking distance--you don't say whether this is a requirement--Cuna is a couple miles north of you, depending on what you mean by "just north of downtown." Easily reachable by cab or el, though.)

If you want something unique - unavailable in Milwaukee and just about anywhere else, I recommend Moto, our most experimental, molecular cuisine restaurant. It is great fun with foams, fizzes, on-table cooking, brilliantly unusual cocktails. Location-wise Moto is a short cab ride from north of downtown. And it is a great favorite of LTHers (a Great Neighborhood Restaurant). Whether you enjoy every dish or not, it will be a source of conversation for years to come.

Moto Restaurant
www.motorestaurant.com

945 W Fulton Market
Chicago, IL 60607
(312) 491-0058

Thanks so much to all my responders! I will check these out and let you all know where we end up! Thanks again.