Monroefiles -- I have the exact same situation with the bumblebees at my house! We can't even sit on the front porch or the back deck without getting buzzed! The big bees just hover, scurry away and come back for more hovering. We also have a screened in porch with lattice across the bottom...the bumble bees get inside the porch and get trapped in the lattice and die. So far this Spring, my boyfriend has already picked out 13 bumble bees from inside the lattice. WOW! He seems to think that the hovering is a form of protecting a source of nectar and possibly a mating ritual. If you pay close attention, you'll see another bumble bee hover over and they will get into a tussle and buzz around until the other one is run off.
It is true that they won't bother you...I don't even think bumble bees have stingers, but it is still scary to see these fat bees buzzing and hovering around the house!
I'm glad you posted this thread as I'm interested in other replies.