The AHA really does try and move it around as much as we can so that folks don't start feeling lonely, but in order to get it into your town, the AHA needs a proposal from your area.
I'll try and dig up the proposal document later if you're really interested, but for a city to host the AHA looks for a couple of things:
One crazy brewer to shoulder leading the whole deal (ok - maybe 2)
1-3 clubs to support running the conference - different tasks for different folks
A strong homebrewing presence in the region since most of our attendees drive from within a couple hundred miles
A hotel with adequate conference space/facilities and a hotel room rate within reason for ~1000 people
If you can wrestle up those things (and Gary and the AHA staff will help out a lot with finding a suitable hotel - so a little less worry there) and the numbers work out - it could come to your hometown.
The group is always looking for proposals for venues. We're trying to get ahead of the game and start planning 2-3 years out. When the local committee has more time, it tends to make for a much smoother experience in June.