REI in Denver is massive, America does outdoor stores well. The REI in Denver even by american standards is massive and full of really cool stuff and keen knowledgable staff. We brought over $500 of stuff, cliff bars, water bottles, socks, softshell jacket, shorts, t-shirts you name it. We held off getting a load of stuff before we left because outdoor kit is significantly cheaper than the UK.
We spent the whole morning in Denver (Almost entirely in REI) then headed out to our first mountain bike destination Fruita CO - oops wrong side of the road . . thats better, off we go!