Covering an iphone

[pizzapizza92]

I just bought myself an iphone and I am in the process of looking for cases. I want something slim and was considering just getting a skin that only covered the back of the iphone. However, I thought it might be best to be safe rather than sorry and opt out to get a flip case that covers the entire thing. The back draw to that though is the phone now becomes bulkier.

Is it necessary to cover everything(front, back and steel sides) on the iphone, or could I get away comfortably with just buying a skin that will cover the back glass part?

PS: I am only considering a leather skin or cover and I already have a screen protector.

Thanks!