In Edmonton, a place even colder than the northeastern U.S., they have an excellent amusement park indoors at West Edmonton Mall. The amusement park is called Galaxyland (it actually used to be called Fantasyland but I think it got changed around the time the internet went mainstream for the same reason WWF went to WWE). It is a fun park, I've been there. And you could go in January. But you'd be frozen if you ever tried that there. And you just can't do it in the cold places in the U.S. Branson would be probably the coldest I would do it if it were up to me. And even then, Silver Dollar City is closed for 2-3 months of the year. They do have a lot of land in Orlando though.