Denver is full of singular experiences. And green chile. And breweries. And... well, you get the picture. Anyways, before you die (or leave Denver, which... is the same thing?), make sure you check off these essentials -- in no particular order.
1. See absolutely anything at Red Rocks
Whatever you're planning -- a concert, Film on the Rocks, a hardcore workout -- you absolutely must go. Actually, this item should probably require a minimum of five visits before it's complete, with some kind of punch-card system.
Lie, beg, or cheat your way in if you have to -- it lives up to the hype and is a must for any beer fan... which, if you're living in Denver, probably describes you.