Good choice on a bus over a motor home. School buses are built like tanks. The best advice I have is to read everything you can on here. You will learn a lot.
I have a large motorcycle too. I'm planning on having a "garage" in the back that will take up at least 10 feet of space. I will run the bike up a ramp into the bus. The rest of the space will be used for storage.
My bus is 38 feet long but right off the bat I'm down to 28 feet with the garage space lost. Lay out your interior on paper and see what size bus you really need.
I'm in PA. I looked at some buses in the Pittsburgh area and found nothing but rust buckets. I ended up getting one that came from OK and it is in much better shape with no rust. Rust is a deal breaker. The time and money you will spend would be prohibitive. Try to get a western or southern bus.
Figure out what you want/need before you start looking and be prepared to spend a lot of time and money. Welcome to our world.