If you want atmosphere (good food, but atmosphere primarily) in a private room then I would recommend the historic Roycroft Inn in East Aurora (about 20 minutes Southeast of Buffalo; easy to reach on the 400). The Roycroft was central in the development of the Arts & Crafts movement in American culture. The architecture, with dark wooden beams and chapel-like features, is a fun/romantic setting for a family occasion. I am not sure of the cost per-person but they probably have an option in the $75 range. The event I attended was a bit large; maybe that's why I noticed some people were less than satisfied with beverage/wine supply. However, I had no complaints and I thought that overall it was charming.