I've used command strips successfully. While they don't seem to come off, be careful how much weight you hang on them. I had one with a medium weight jacket hung on a command hook. It pulled the wall covering away from the wall over time resulting in an outward bubble stretching the wall covering. Fortunately, I was able to get it to flatten back out with a hair dryer.
I think most pictures would probably be okay. A towel rack....not so sure.