Much as I am hesitant to suggest it, you might pick up a few Rick Steves books. He is a big fan of B&B's in Europe and reading his reviews and suggestions about B&B's can give you some insight into what he sees as benefits and recommendations. Most libraries have his books.
There are a lot of web sites and blogs that talk about the joys and sorrows of running a B&B in the States. Most of the ones I have skimmed are fast to point out it is a LOT of work but usually very satisfying.
Good luck whatever you choose.
Just Some Consultant
"I never understood the dread term "terminal illness" until I saw Heathrow for myself." Dennis Hopper