Bicycle Village (303) 750-1064 - Super Store, expensive, kind of cheesey in a suburban way, wonderful service and not too expensive, this is the gart people taking a crack at Bikes.
Big Ring Cycles (303) 216-2000 - chill, high end stuff, ok service, good fits, ask for Dennis, you can get it all here, this is my reccomendation, deal makers, roadie and tri stuff
Bike Source (303) 221-4840 - Chris in the tri shop is a good guy, super store, very expensive, kind of cheesey in a suburban way
Bike Werx (303) 399-2453 - just re-opened under new mgmt/owner
Colorado Cyclist Inc. (719) 591-4040 - so expensive, and cheesey in a Colorado Springs way, used to be cool, far from Denver, not worth the trip
Denver Spoke (303) 777-1720 - cool guys, excellent service, good prices, very Roadie
Excel Sports (303) 444-6737 - Boulder, expensive, if you can think of it they have it, but you will pay, good sales sometimes, pretty roadie too
Schwab Cycles (303) 238-0243 - nerdy, but low key and high end selection, these guys are edgy in that roadie kind of way
Turin Bicycles (303) 837-1857 - very expensive, thugs in the service dept, very expensive, lame selection
Wheatridge Cyclery (303) 420-5620 - possibly the worst in Denver but MASSIVE selection, very very expensive, expensive service. The ONLY reason to go here is to see the bike you want, check it out, then go somewhere else or online to buy it
Sampson Sports (303) 691-5650 - cool guy, a little weird, custom rigs, expensive, some people love it, some people hate it, high end parts too