I've displayed my photos in a coffee shop with great success. I chose a theme that was relevant to the area. I printed only live music photos specifically shot in local venues. I also chose images of bands that I knew were popular rather than my own favorite shots.
I printed the photos myself on my Epson 4800. I also framed and matted them. I used mid-priced polycarbonate frames, these look professional, don't chip or scratch like wood or metal and won't break the bank. Total cost was about $400. I easily made it back and even though the display was taken down 6 months ago people still ask about prints. I actually sold one on Friday.
Another key is to keep the prices affordable. The biggest mistake I see artists making is overpricing the art. Keep in mind the clientele of the venue. The place I displayed is mostly patronized by hipsters and college students. They're not the most affluent crowd.
You must also realize that this isn't necessarily a profit making venture, but a marketing strategy, keeping your prices down to a reasonable level will encourage more sales. I spend a lot of time in cafés and I most often hear people talking about the ridiculous prices on the art, and I usually agree.
Some of my unsold prints from the show were donated to special causes to be raffled off as well. I donated a photo of Motorhead to be raffled off to help a local band buy a new tour band when theirs was stolen. When they needed photos for their new album, guess who they called? That print that cost me about $25 to make landed me a $750 gig with more on the horizon.