The weather is clearly your concern. Colorado and New England are certainly high on the list in terms of nice places, but winter is a big problem. I'd rather go on a 2 week trip to the mountain in the snow, than spend 6 months waking up early on the morning with a shovel in one hand and a bag of salt on the other hand :)
I live in Denver and I only have to get my shovel out about 5 times a year. Coming from the Midwest, the winters here are amazing, comparatively. There's plenty to do in the winter and the mountains are great.
