One big part of Downtown I noticed you missed was 14th Street and the entertainment district. Not only does this include the Denver Center of Performing Arts (largest such in the nation outside of New York), but this part of sowntown also happens to have two skyscrapers under-construction and a third high-rise in the foundation construction phase. Perhaps all teh construction kept you away? Anyway, that will be a must see in a couple years.
and by the end of 2012, you'll want to check out Denver Union Station all over again. Because see that sea of parking behind Union Station right now
in this photo you took, well that is being redeveloped into a Union Station Multi-model transportation hub.
Just click here to see the plan.