Well, since you have shitty taste in beer I won't go into that analysis, but otherwise....
Both of these areas are beautiful. I'm obviously more partial to Colorado, and as somebody who has lived here for almost seven years I completely disagree with the people who said 5-6 days is pushing it for a stay here. You will not run out of things to do. Lots to do in the city and surrounding burbs, plus you have the mountains and lots of amazing scenery nearby (that you would not have to camp to see). Rocky Mountain National Park is not only gorgeous, but also full of elk that time of year because it's mating season. Very cool time to visit.
Oh! You could eat at the legendary Casa Bonita on your way to Red Rocks, which will still have concerts going in late September.
There's Colorado Springs, Boulder, Fort Collins, all cool places to visit for numerous reasons. I could give you a much longer list if you want it, and I fucking promise it would keep you busy for your whole trip. Also, the weather is normally pretty awesome that time of year. They say we get "300 days of sunshine," which is probably an exaggeration but pretty close.
Seriously, come to Colorado. I promise I won't sneak into your backseat and breathe heavy.