In the book I’m writing now, part of the story takes place in a real restaurant. I not only mention the restaurant by name but I name the owners as well. I asked for their permission, but should I get it in writing?
Absolutely, and you need to have an attorney draw up an agreement that prevents them from ever suing you or any of your future publishers for any reason whatsoever.
Unfortunately, many people assume all authors and publishers are rich and some may even maliciously give verbal permission with the intention of filing a frivolous lawsuit later. Don’t make the mistake of thinking, “Oh, they’re such nice folks. They would never do that.” Frivolous lawsuits are filed on a daily basis in our country. Some are even filed by family members. Unfortunately, there doesn’t seem to be any shortage of unethical lawyers who encourage it.