I've got the Speck candyshell case in pink/white. It looks awesome on my white 4s. I also have an uncommon case from the Apple store. Waiting on otterbox to get the white/pink option. And yes, I do like accessorize my 4s. It's what I do.
I got a clear Griffin Flexgrip for the time being while I'm looking for a more permanent case that I like. Nothing's really catching my eye, though. I quite like this one in either white or purple but that's about it.
Oh and I have Power Support Crystal front & back protectors. Not the cheapest screen films out there but I like them a lot.