Sunday Bunch - Group of 20 - Private Room?

The title says it all. I'm looking for a place to host a group of 20 or so people or a Sunday Brunch in December. It needs to be more or less centrally located in the city (between Chinatown and Wrigleyville) and would ideally have a back room that could house our group so we don't disturb the rest of the patrons.

Two years ago, we held this annual event at Prairie Fire, and they promptly closed the next day. Last year, it was at Ann Sathers, which worked out OK, but was a little on the crowded side. This year, I promised the group that I would come up with some new suggestions. What do you think?

Off the top of my head:
http://bistronomic.net/hostalt/private-parties/
http://www.southwaterkitchen.com/private_events.php

They serve a tasty brunch and have a lovely private room at Nightwood. I've sat there before and it's a bit rustic -- Basque-style tables and bench seating, iirc. I'm not 100% sure about the seating but even if I am, it may be adjustable and therefore, worth an inquiry.

=R=

Perhaps GT Fish and Oyster. I'm a sucker for brunch cocktails. I don't know their requirements (minimum party size? deposit? ability to order of the menu?) for the Whale Room, but per their website it sounds promising: "We are now hosting private events, seated brunch, lunch and dinner for up to 40 people."

Mercat a la Planxa offers a nice three-course brunch. I can't quite picture the seating options for your group, but given it's in a hotel, I assume they are accustomed to groups and have a plan for twenty.