I smell a East Coast bias here for most of these locations.
Sure the USGA hits Olympic, Pebble, and now Bandon every now and then on the West Coast. Is there really a dearth of courses they will consider out this way? 
Kalen:
Let's see...Far Hills, N.J...East Coast bias? Couldn't be...
Remember that the USGA's site selection is a product of a lot of factors, geography being just one of them. I do think the USGA wants to move the really big tourneys -- US men's and women's opens, US men's amateur, maybe the US senior men's open -- around the country for geographic balance, so fans (and corporate sponsors) in certain parts of the country get a chance at seeing (supporting) one of the big tourneys at least once a decade, if not two or three times. But my sense is that with the rest, it's a combination of: course suitability; wanting to mix older courses with newer, worthy ones (Kinloch being a good example); membership willingness to host; public accomodations; connections of club owners/membership with the USGA; and even weather (as in, Florida is unlikely to get a big, mid-summer tourney).
I actually think the USGA deserves a lot of credit lately for seeking out some really good, slightly below the radar (for the non-GolfClubAtlas fanatic) courses for tourneys -- Prairie Dunes twice in recent years, Newport twice in recent memory, Bandon for the Curtis Cup, and now Lancaster and The Country Club in Pepper Pike, Ohio (two of Flynn's best). I think that type of exposure helps build support and appreciation for the kind of design elements often favored here at GCA.