Wi-Fi Alliance offers its own directory: This hotspot directory includes 9,000 locations that have registered themselves with the Wi-Fi Alliance. In the original flavor, this was supposed to be an expensive branding program, initially free. Now the site's for providers section says, no, it's free, and you just have to meet these minimum requirements, which are pretty minimal.
I have a partnership with and write for JiWire (see all over this page, for instance), so I whatever I say will certainly be read as colored by that relationship. So don't listen to me. Visit _____________.org's rundown of hotspot directories.