Amazon is going to be looking to build a major campus (say 5-10 big buildings) right in the center of town (as they've done here in Seattle) and that's just not feasible in expensive cities like LA, Boston, NYC, Chicago or DC. Denver is too far west, Miami, Atlanta and Raleigh too far southeast. Newark and Philadelphia don't have a sufficiently developed tech scene and as satellites of NYC have a price premium. There's no way Seattle and Dallas are going to form a family, Austin looks great on paper but I doubt they're hungry enough to offer sufficient incentives. Don't know why Montgomery County or Northern Virginia are even on this list.