Calitera is a bit of a hike (at about St. Clair and Erie) but it could handle a group that size and the food is excellent.
Rosebud on Rush could do it, but the food is good but not great.
Mity Nice is in Water Tower Place. I assume they could handle the group. For they do, they do it well.
Of course I'm sure that the Ritz Carlton Dining Room could find room for your group.