A bag burger is a chessburger from the Bag & Kettle at Sugarloaf at the base area and they have really good burgers, pizza, cheesburger soup, and beer. It doesn't come in a bag which is what I first thought.
Bretton Woods is a blue cruising paradise with some fun easy glades to learn to ski trees. Their blacks are really blues and I think they added some terrain if they get enough snow.
Loon is fun on weekdays and has varied terrain and is also fun. They have some nice intermediate bump runs to learn on as well.
I have never been to Stowe but I want to go.
Tremblant has awesome condos and good food but it is a hike, it is cold, the conditions are iffy, the mountain is small with flat spots, and it can be crowded.