For my 3G i went with one of Apples crystal covers for the screen, which was easy to wipe clean of finger prints as heard that the screen looked worse without. Was wondering the same for the iPhone 4 if to get a screen cover or not.
I'm going to prob get a Sena leather pouch again as the felt lining was good as it cleaned my phone when ever i put it in, also stopped it from getting scratched from keys/coins etc when in my pocket.
The bumpers look nice but also like the aluminium on the phone so would be shame to cover it up. Also exposes the front and back in pocket..am going naked when it gets taken out of pouch.
Saying that maybe iPhone 4 will fit in my old 3G sena pouch am sure they are similar sizes