Colorado?

Sorry about being so vague, I was in a hurry. I am debating changing my summer vacation plans. Last year we spent two months touring the West. This years original plans were to head out to Maine and cruise down the coast a little bit. I am having trouble getting excited about that trip after being spoiled with seeing the West and also knowing that we missed the entire state of Colorado. I will have about 3-4 weeks to spend in Colorado during the month of July. I will definitely be going to Rocky Mtn NP. Any other ideas or suggestions will be greatly appreciated.