Denver real estate has appreciated, but it is still less expensive than Seattle, New York, DC, or California.  RTD's prescient build-out of light rail, with a new stop (or even a line) at "Amazon City" will be a big plus in a bid.  Denver's mayor sounds like he's all in to compete in a bidding war, but state help will be needed.  Amazon has not required a downtown location, so there is lots of space available.

The numbers are spectacular:  50K employees in 20 years (enough time for planning and building infrastructure); average salary with benefits = $100K; that's a $5B payroll; 8M square feet of office space, lots of construction jobs; low-polluting industry, especially with mass transit; educated workforce who can tell the difference between truth and truthiness.  It's all good.