I would highly suggest going to Yellowstone if you have not been. It's in Wyoming and usually fairly chilly, though it's been a while since I've been there. I have gone like 5 times though, and there is always something more to do there. We've stayed in several places, the Snow Lodge cabins, by the lake, and in the Inn, and staying in the Old Faithful Inn is my personal favorite. Everything is so old and the wood is so smooth and stuff, it's just amazing. Just hanging out in the lobby after dark is really fun. They usually have some kind of pianist or band playing some nice music (my mom kept wanting me to go play the piano when there was nobody there

). It's so peaceful and comfortable in there. It's very hard to get out of the chairs once you get comfortable

.
Yellowstone is an excellent place to get good exercise with all the hiking and walking. There are so many amazing geysers and hot lakes (The Grand Prismatic Spring is another of my favorite places, though you need to get up high to see its true beauty). Another thing I really like there is the food. So many places to eat, and most of it is quite reasonable. I especially enjoy the Lower Hamster, though I don't think they call it that any more. The cook makes the food on a giant grill right in front of you, and it is quite fascinating to watch, not to mention the food is fantastic. We mostly ate breakfast there, but they serve all meals, I believe.
Anyway, good luck with your trip. Have lots of fun!
Brijar!!!