I have a 9-row bus. It's got a DTA360 Navistar engine--same displacement as the 5.9 Cummins, but 400# heavier. It's a Fuller 6-speed and we get 12mpg with it. I pulled the 4.78 pumpkin and have a 3.73 to put in, which I hope to do this weekend. The worst thing about a bus is the interstate. With 4.78s my bus has made 69mph max on level road. That's with a motor with a 5" stroke spinning 2900rpm. The pistons must be doing the speed of light. The worst thing is, you go into 6th at 45mph, which means that on a hill, you have no gear to go down into until you are dragged down to 45mph. When I get this new pumpkin in, I expect to kick ass on the interstate. I don't use first now. I will use first and have a gear to go into and still maintain speed with the new chunk.
A bus is loud. Mine is filled with carpentry--one side is bunks and the other is booths--cabinets all along the roof. Also, the ceiling is deadened with B-Quiet Ultimate. This year I'm building a roof platform. We have an AC unit on the roof, a big Generac RV generator and my house is set up so the bus can power it during outages. A 5-row is pretty short. With a 9, we have a bathroom, a kitchen, 5 bunks, a leather couch that folds down into a double, 2 dinettes that seat 8 total (all with belts) and a pair of leather seats from a Dodge Caravan that recline. We have cabinets lining both sides of the ceiling above the windows with a built-in sound system that kicks ass. We have had 20+ people packed in during a thunderstorm at a state park and it was no problem.
I think a 5-row is cool, but to short to do much with. An 11 or 13 is more common, but too long to make maneuvering easy. An 8 or 9 is perfect.
I also installed a UPS jump seat over the stairs so one of my kids can keep me company.