I experience two types of bus drivers:
Those that are extremely patient and considerate, staying behind me until thier stop knowing I will have to pass them at the stop if they pass me earlier and generally giving me plenty of room.
And the occasional A-- that barely makes it past me before pulling toward the curb for a pick up (not even getting parallel) then doing nearly the same at the next stop.
I usually only encounter buses on 4 lane streets so I make sure I take enough of the lane that they don't think they can squeeze by. This helps with most of my encounters. I experienced more close calls and dangerous passes in the first 3 months I commuted when I lacked the confidence to take a lane than I have in the last 2 years since I learned to ride like a vehicle. I also get fewer flats that way also.
Craig