Recommend getting a Seidio case for certain.
If you get the rubberized one, it is thin enough that you can get their holster for it that has the magnet.
If you do get one, order 2 at once. Eventually you will need to replace it, and can save on shipping.
If you ever drop the phone the case will be a life saver. I'd also suggest screen protectors as well. Several companies to choose from here too. I get mine from Screen Patronus. They hold up great, specially used with the hard case.
Search on "Seidio cases" and you will find many long threads with others feedback on their choices.