I lived about an hour north of Colorado Springs for 3 years, and have never been to WA so I can only talk about one of your options. I love Colorado and would move back there in a heartbeat! There are some sick national parks well within reach of Colorado Springs and spending a weekend in Denver picking up some super fit chicks would be pretty easy as well.
Denver to Vegas is only an hour and a half flight, and with SouthWest it's super cheap too! Some of my buddies did it for a roadtrip, but a one way flight for $70 and getting drunk on the flight was a better option in my book!
I'm sure you could have a fun time in WA too, but if given the option I would go with CO. There are 51 (I think I have the number right) peaks that go up over 14,000 ft in Colorado. See how many you can knock out in your short time there.