I have been commuting to Denver for the better part of the past two years. I cannot comment on the two properties you mentioned except to say you can't beat that price. Plus most, if not all, of the downtown properties would hit you for parking.
As for the tour of the US Mint. The tour is less than 30 minutes long. When I tried to go, the line was over an hour long. So we passed. A co-worker went and said it was not worth it. But I still plan on trying.
The bookstore out by Cherry Creek is The Tattered Cover. There is also one on 16th Street, down by Union Station. If you love all things books, either one is worth an hour or two of your time. I have killed many a lunch hour there.
I recommend Ocean Journey for part of one day if you don't mind being indoors. They just opened a shark exhibit that is getting high marks.
I also recommend a trip up to Boulder and with a stop on Pearl Street. Great people watching.