I grew up in DC and then moved to CO in 85. You're right - it's not fair to compare the depth of "cultural" activities between the two cities. However, Denver has plenty for my tastes. There's major and minor league sports in every flavor - the Denver Center for Performing Arts (DCPA) does a great job - the music scene is fair for both small and large venues and the cusine options basically suck. Okay that was a little harsh about the food. Regardless, I prefer to cook and eat at home.
IMO, the crown jewel aspects to Front Range living are friendly people (although with a growing population this aspects has already started to wane) and access to the CO Rocky Mountains and the UT Canyonlands. Just an hour west by car and you'll have Skiing that rocks and cycling that rolls.
Welcome to the Rockies