I'll second that -- I loved living in Downtown Denver, and still visit as much as I can. Funny, when I was reading about the seven-minute commute in Nashua, I thought "that sounds like the commute I had in Downtown Denver," then saw your comment.

I'm now living 6 miles out in Olde Town Arvada. It's actually a neat walkable area with coffee shops, brewpubs, etc., although there are no major tech employers within walking distance. (I work from home.)