I'm embarking on a project soon. It doesn't involve getting releases signed by anyone though. My advice is to print off a handfull of release forms and go for it. Do not hesitate. You can at least shoot building exteriors to start, and schmooze the establishment owners for permission to shoot interiors. You dont necessarily have to shoot patrons, you can photo interiors while empty, or get the staff only. I'd venture a guess that most places will jump at the opportunity, especially if you hand out complimentary photos to hang on the wall.