If you're near a University, check out their library. Most of the time they'll have a cafe, guest wifi, and a reasonable amount of white noise for a library.
Yep. I live a mile and a half away from a university and I use their library for working on side projects. I've found it to be a great place for helping me focus.
Years of schooling have programmed me to think that the library is where you go to be serious about getting work done, and I'm often more effective there than if I sit at my desk at home.
I've written to my local library organization suggesting cafe areas in some of the bigger libraries. Never heard back, but I really hope they think about it. It could raise some money and improve patronage. The local library is much more convenient for me than the coffee shop, but I need to be eating/drinking when I'm working on something.
I was surprised when I found that the library close to my place in London (at Swiss Cottage) has a cafe inside and seems to have a relax policy on eating snacks inside the library.
They also appear to let you bring your own food and drinks. I've seen moms break out a box of Capri Suns to give to their herd of children and people unwrap a footlong from Subway in the Barnes and Noble Cafe.
I've worked from a library a few times recently. Security is important, but there are libraries that don't have this problem (might depend on the country, though).
Other points I personally regard as features that help me focus. If wanted to get some food, I'd go to a café. To meet someone in person or make calls, an open space (if there isn't any, a café) is a decent option. But if I want to concentrate on something for a couple of hours, I personally go to a library.
Depends if they can handle the infrastructure though. Auckland Central Library in NZ was right next to two universities which meant that during the day all seats were taken up by students and the internet slowed to barely able to connect. Newcastle Library here in the UK has such iffy internet that you can barely connect.
This hasn't been a problem in my experience in Chicago (and to a much greater extent Oak Park). In both, there were lots of homeless people around the library --- but they weren't at the same table as you, and they didn't disrupt anything.