Always sealed for BB's. Overhauling BB's just seems like more of a pain and you only have so many times you can take off those cranks and put them back on square taper before you're deforming ****.
Hubs, either or. Depends on how much work you want to put in. Personally I'd rather spend time truing my wheels or something. Bearing overhaul isn't that hard per se, but readjusting the cones after the repack is tedious and a pain. Plus if you care about such things as drag, sealed bearings can get damn smooth if you're willing to pay the price. That Phil carbonyte bearing stuff is looking buttery.
But yeah, if you also like to say, wash the dishes, you might like overhauling your bearings.