Horn & Cantle, Buck's T-4, Cabin & Lotus Pad are good and $$$$. A yurt dinner or sleigh ride are a lot of fun. Yurt is BYOB and has sledding between courses & a bonfire. The sleigh ride dinner is more romantic and has live music. Not a fan of Olive B's, but others swear by it. Like most resort areas restaurants are expensive and most serve average food. The River House on 191 has good BBQ, great views and is reasonable but gets crowded quickly.
Yellowstone snowmobile or snow coach, horseback riding at Jake's (all winter), snowmobiling, skijoring on Sun PM at the 320, zip-lining, snowshoeing, dog sledding, ice skating, curling and ice hockey.
Big Sky has many signature runs for all abilities. Tram laps are signature and more fun with good visibility and fresh snow. There are some good tree skiing runs, bowls, chutes, groomers, terrain parks and hike to cliffs & chutes.