The good bet is that Amazon will want to locate in a place that has the same attributes as Seattle, but somewhere serving the East Coast/Midwest/ Southeast population centers. Anywhere west of Dallas is probably eliminated.

Amazon will be very protective of its hard charging, but cool vibe culture, attractive to driven, techy, digital-oriented younger professionals, who want a place with recreational and entertainment attractions fostering comfortable lifestyles. If you have two headquarters, people will be shifting back and forth, so you want a place where people in Seattle will want to go and visa verse. That eliminates places like desperate Detroit and other Rust Belt relics. Pittsburgh is touted—Carnegie Mellon offers a high tech university link, but it is small scale and offers little to match the recreational attractions of ocean and mountains in the Pacific Northwest.

And Pittsburgh lacks an essential transportation hub nexus. At present, Amazon benefits from the large Seattle port, but is about as far away as it can get from Eastern gateways, which link across the country and to the rest of the world through various international airports, interstate junctions, and seaports. For a company dependent on logistics, tapping directly into a transportation center would logically be a must. FedEx has made Memphis into a shipping center, but Amazon won't attract the workforce it wants to a secondary or tertiary location without at least some bright lights, big city attributes. And it probably wants some nearby major university talent to draw on. Strike any of those candidates which don't fit this picture.

Chicago is always a possibility, because of O'Hare and its 24-hour city features, and it has wide open spaces to develop west and south of the city. Northwestern and the U. of Chicago offer intellectual muscle.

Although they boast the transportation infrastructure, Dallas and Atlanta don't match up well with Seattle on business culture, politics or local sensibilities—it's like oil and water, literally in the case of Dallas. Denver would be a better fit, but it is too far west to make sense.

That leaves the New York area, which is probably too congested and has too much going on already. Amazon's impact would be less noticeable—the company could draw on a huge talent pool, but it would be harder to retain talent given all the competition for it. New Jersey has put in a big play for Newark, but would that fit the Amazon brand? No.

And then there is the Washington, DC area up through Baltimore. Jeff Bezos already owns the Washington Post and moving in the vicinity would boost further his political clout. It's a prime gateway with all sorts of airports and road intersections, feeding into the Northeast, Mid-Atlantic and Southeast. Baltimore is a major port. And there is plenty of university talent with Georgetown, GW, and Johns Hopkins–young people already flock into the area. There are also plenty of development sites, not to mention a major cloud computing data center complex in suburban Virginia. Amazon lives off cloud computing.

The DC area–that's my bet.