The choice is going to come down to MONEY. Amazon announced this the way they did to set off a bidding war among desperate cities and states. Colorado will not offer anything remotely like what a desperate state like Texas or Massachusetts will. And rightly so. Purchasing jobs rarely pays off for the "winner." As to what Amazon needs - at the moment their Seattle HQ employs 21,000, not 50,000. Ask people who live in Seattle about Amazon's promises - and what they actually deliver. Or ask folks in Aurora where those great jobs in the distribution center pay $12.50/hour. Try living in Aurora on that income. 

Denver and Colorado are booming because this is a great place to live. No hurricanes, no earthquakes, maybe some fires in the mountains. We don't need to bribe anyone to move here. And it might actually be good if we took a breather on the growth for a while.