You'll make a great decision if you choose CO...can't go wrong living in the Rockies. This is my 3rd time back through the state and I plan on staying put for a long time.
There are so many great places to live...I've been up and down the front range from Ft. CollieDog (what I always called Collins) down to the Springs. It depends on what you like...
Ft. Collins...nice college town, that can get overwhelmed with 18-22 year old...Horsetooth Res is a fun place to hike and such. The Cache La Poudre region has good fishing and places to trek through. Benefit: small college town, pretty area. Con: Pretty far up north, if you end up wanting to trek the central trails you'll be driving quite a bit.
Denver Region...it's a major metropolitan area what can be said about a city. Lots of traffic and people. Me personally if I were live back up there again I'd hug the Jefferson County/Boulder County/western edge of Douglas County for easier access to the mountains and such. Towns like Parker or Aurora aren't bad, but they are what I consider Kansas Lite...gets a little too flat out there for me.
Monument...a great little town to live in. Easy access to Denver and the Springs. Not a hotbed of economic growth, but hey it is a small town, friendly folks and laid back mantra. People who live there are working in the Springs or Denver region.
the Springs...good size city with all the amenities and you live in the shadow of a 14er.
I can recommend an excellent realtor if interested. I'll pop a PM to you with his name and contact info. He works the entire front range, knowledgable and one helluva negotiator.
@Asman same area as you