Allen,
Denver is a pretty city but the real Colorado is when you leave it. Try Boulder to teh north, college city but very small. Highway all teh way there. I'm presuming that you 'll be doing the Rocky Mountain NP, I came at it from Estes Park, quaint little village. Park is breathtaking. Head to Aspen/Vail after that its magnificant. Colorado river is amazing. Have a ball!