Gordon Biersch does a private room for larger groups. The set menu price includes beer (at which point you can make your own fun). The food is okay, but not stellar and probably not up to CH standards.
It's not outstanding food, but I know Palisades has a private room that you could probably seat 30 in. It's got a great view of the water and it's close to downtown. Nothing out of the ordinary, but you would be able to have a room to yourselves.