Here in the Atlanta Metro area, we have two BMW motorcycle outlets (that I know of). The one closest to me is in Marietta, and has been okay to deal with in the past. I have ordered parts there, but found online parts ordering to be more efficient- the parts folk at the dealer were not too well informed, and often got parts mixed up, and, it's a 30 mile ride each way.
As for buying newer bikes, they seemed to have kind of an attitude, since I often rode my '71 R75 in, or my '78 R100..they'd never even look twice at me. When I rode the ST13 in, they at least said Hi.
The other dealer, Blue Moon cycles, is SO bad, I'll never go back....they are the quintessential snobby, " we sell BMW's, so you owe US", BMW dealer. John Landstrom used to own it, am not sure now. He was, at one time, a fair wrench, and knew a lot about Airhead BMW's, but became pretty successful, and it went to his head. Not a place I'd recommend nor patronize. I hate to bypass local places to buy online, but this is one case I will every time.
Our local Honda Dealer, (Cycle Nation) is not much better, but the parts gal is pretty good. Thank goodness for online parts places!