Are there any good antique stores in the downtown Denver area?

I can't speak for for downtown, but antique row on South Broadway is awesome for antiques! While you're down that way, you have to check out the Black Crown which is an antique store / restaurant / piano bar - quite fantastic! If you happen to fall in love with the chair you're sitting in whilst sipping your mimosa, you can just buy it and take it home with you. Check them out at http://www.blackcrownlounge.com/