Do not buy a silicone case from PDAir, he's too soft, does not hold a shape, I have it stretched out and now it's hanging on the phone.
What covers you tried?
Ive got the commuter as well. The most protective case I've ever had for a smartphone. And the screen protector it came with doesnt seem to get scratched.
I really liked the Incipio feather case, but it was not very sturdy. I broke it from putting my Venue in and out of my pocket. The pieces on the edge just broke off.
I like the Commuter case, even though it is a bit bulkier. The plugs for the ports work much better on the Venue case than they did on the Streak case.