I live in Grand Junction. I am a native. Good suggestions above. There are so many areas to explore and visit. We are Blessed with a plethora of incredible areas and terrain to experience. Moab, the San Juans, Ouray, Telluride to mention just a few. You could spend weeks at each one of the mentioned areas. My personal favorites are the Moab area, which encompasses a lot of area, and Ouray, which is in the heart of the San Juans.
Telluride is amazingly beautiful, but I prefer the Ouray atmosphere. Its a little more laid back and not quite so "Aspenish".
I would suggest at least 4-5 days in each area. The two I suggested are vastly different in geographic attributes. The visual aspect at the top of any adventure. The thing great about our area is the diversity. Desert to 14000' peaks in an hour or two. Be flexible with your time as you will be spell bound with the terrain.
Sam