With buses I take a break, the few minutes to let them clear the area is easily worth it. leap frogging each other isn't worth the mental exercise of trying to figure out where it's safest to pass one another. The tour buses I deal with are the one's that drop off tourists at the motels on the beachside in Miami, FL. As a cyclist, I have to realize they are doing their job of delivering tourists to stay here for a week or whatever. So they will be driving, parking, loading & unloading people and luggage. I give them their space & time. When I do ride around them, I am cautiously slow. Same holds for cabbies and city buses. It can be annoying & inconvenient, but a couple minutes is far better than the alternative of being crushed by one of them.