Case wise, I opted for the Rock Quicksand. Much sturdier than the original back and keeps the back and sides from getting scuffed and scratched. If you're after something heavy duty look elsewhere. This is a very slim, very durable case. I'll probably look for a leather flip case at some point, but until then this will do very nicely.
Screen protector wise, I went for the invisibleSHIELD. Mainly because the phone arrive way earlier than anticipated and I didn't feel comfortable walking around with it completely naked and this was the most readily available one to me. There are other recommended brands, but I can't recall off the top of my head. Think I've got a thread here somewhere with people offering some brands.
One thing I will say is steer clear of the cheap stuff, Zagg's invisibleSHIELD comes with a lifetime warranty so anything goes wrong just get a replacement. It also looks pretty damn good. I only ever notice it;s on if I look at the top or bottom or really look for the orange peel effect. The latter is only really noticeable if you really look for it in the right light.