Part of me thinks that finding a willing local committee to get the legwork done is also a big factor. The process for getting a future site selected isn’t exactly well published, so having some available people that have done it before (at the very least in an advisory capacity) is an advantage that places that have already hosted have over new sites.
The conference is too big for just about any hotel, so it will be in conference centers. The folks I know in the Indianapolis clubs would love to host. The conference center there is large enough and has many connected hotels. The drawback is that the conference center is booked far in advance with conventions that are there every year in June. So the dates often are determined by an available slot that the city can host.
Another factor is the local alcohol laws. That takes some places out of contention.
Some locations are too expensive for the frugal Homebrewing community. Think NYC, and so on.
Air transportation is another factor. Hard to get to places like Bend OR by air for most of us (it does have an outstanding beer scene).
The AHA/BA has a lot to sort through to select a host site. One thing you can do is fill out the questionnaire sent out after the conference. That is one way they gauge interest in the potential sites and where the members become price adverse for hotels.