You'd be better of narrowing the field to things that appeal to you and then asking what folks think of them. A broad 'what should I get' usually ends up with little more than a listing of what people have. You are right, there are a lot of choices, but it's like asking 'what kind of car should I buy.'
Take a look at
www.ipaqcases.com to get a smattering of what is available. If cost is a factor, be aware that in most cases (pun intended) you get what you pay for. I have always been pleased with SENA cases if you like a leather flip case. Good quality, decent prices.
Screen protectors are the same. Most folks are fairly passionate about the ones they are currently using. The PPCTechs ones seem to be the cadillacs. They are not cheap, but most who have them swear by them. Not sure I would waste the money on 50 cent screen protectors. (not a fan of their music either)