I've gone for same old Zagg skin front and back for the 4s probably add a bumper from apple or one of those metal bumpers with the 2 grub screws that keep it attached. If you order the Zagg online you can have it printed with a photo etc, I have just bought off the shelf scratch proof clear.
Mili and morphie cases are ace if you use the phone a lot, protect it well and give you a secon battery.
The ultimate protective case (or one of) IMO is the otter box defender
The other end of the scale is a few packs of clear protectors front and back off eBay for dir cheap and an apple bumper or even 'fake' apple bumper
pagids in the post? Yhpm about master cylinder :p