If you're hard on a phone like I am, the
Otterbox Defender may be what you need.
It has a screen cover that will protect from liquids and scratches. It is rugged and provides very good protection. It is bulky, but I don't think you can protect well and not be bulky.
Since you've already ordered a case, this advice might be too late. I would recommend a screen protector - any of them will provide some level of protection against scratches. Look for a clear one. In my experience the matte finishes are horrible and mute your nice screen resolution.