Decorate. You'll need a good deal of material for the curtains (at least 50 windows on a full-size bus) and other aspects of decorating will take time and money, again due to the size of the vehicle. Think of ways to spruce up the interior.
Re-arrange seating. The seats of a school bus take up so much of the available space, it's likely you'll want to take at least a few out. Taking out seats will also lighten the load and improve fuel efficiency by at least a little.
Modify the front door. The unique pull-lever door system of a school bus can be difficult to maintain, and it's more complicated than it needs to be. With a few shop tools, you or a mechanic can take out the "folding" door and replace it with a simple one-panel that you open with a latch, thus making your school bus simpler and more adapted to non-school use.
Run appliances off of the engine. As with any other vehicle, you can "plug in" small appliances like a camping stove or a laptop computer to the vehicle, accessing the battery power. Be sure you research how much power you have available so you don't drain the battery entirely.
Change the paint job. A school bus doesn't have to be a strange, off-color between orange and yellow; the uniform hue of the vehicles is to mark them as resources of a school district. Re-painting the bus helps make it yours and prevents all kinds of confusion.
Soup up the engine. You probably don't want to try adding "turbo nitrous" or other supercharge systems to a school bus, but you could ask a mechanic about getting a larger engine into the vehicle to help get you around better. However, due to the way these buses are built, they're really not for joy-riding, and for low-or-middle-income buyers, they usually end up being mostly stationary.
