Well, everyone else has already told you where to get samples. Just don't stock up on anything until after surgery. Many people find things taste different after surgery and something you love pre op might taste terrible post op, especially in the beginning.
Also, keep in mind that the way you make a protein shake really changes the way it tastes. You can mix most powders in either water or milk, and that makes a big difference. Most of the I like to put in the blender with a handful of ice, but some brands get way too foamy for me in the blender. Some you can just put in a glass and stir, but many brands will leave icky little clumps if you do that. You can do hot protein drinks, too, and you can add other stuff besides just protein and liquid.
Please note: I AM NOT A DOCTOR. If you want medical advice, talk to your doctor. Whatever I post, there is probably some surgeon or other health care provider somewhere that disagrees with me. If you want to know what your surgeon thinks, then ask him or her. Check out my blog.