What an awesome thread! Denver reminds me of a much more mature Calgary, which being a couple decades older and 3x the size, I suppose is apt
Great pics!
EDIT: Haha wow, there is a Calgary - Denver comparison already happening here? Well I guess there you go. Now I don't feel like a jerk for saying it
To answer the question, I would say that both are pretty comparable in walkability, with an edge to Denver, given its massively larger population and its greater historic built form. However, Calgary is developing much faster, with over 30 high rises and countless low rises UC, to Denver's 7 high rises and I'm not sure how many low rises UC, not including Calgary's dozens of proposals. So I'd say Calgary has the more infill, fewer surface lots in the downtown for sure, but Denver has the edge on walkability for the greater downtown area at the time being.