Most of the buses are great for Sunday games, make sure you get one of the buses which get there 3 hours before though, its not a true NFL experience without the tailgating. Rallybus and Bus.com I have used in the past and both are fine.
For anyone using the buses for the Colts game I would think twice though, they can be an absolute disaster for Thursday/Monday games. They leave downtown Boston at 4/5ish which turns the normal 30 min journey into an hour, hour and a half sometimes. Likewise the patriots train can be appalling on Thur/Mon games as it normally has the line pretty much to itself on Sunday games but often gets delayed because of commuter services on weekdays.
Anyone going to be about into the weekend after the colts game? I've delayed my trip so I'll be around until the Monday in the hope of catching some Sox post season action. Probably going to just stay in Boston at my grandparents place for my trip unless someone wants to share at the Hampton on the Thursday?