All I can say is that I have made quite a few American friends who have been here for a year, and they have all loved it! Throw yourself into it, get involved in whatever interests you - the sports teams LOVE Americans because they are so much better at it than we are!
All the colleges are fine, I am in Cartmel and like it because it is nice and new and a bit quieter than the ones on main campus. If you are a really lively sociable type you might want to look at the colleges with older (cheaper) accommodation and more people sharing a kitchen, like Bowness or County.