Pick 2 RB of 4 or 3 rb and sit an extra reciever?

I have Rashard Mendenhall, Knoshown Moreno, Brandon Jacobs, and LT. Also i have the option of starting a 3rd RB and only starting 2 WR. For WR i hav Brandon Marshall, Greg Jennings, Mario Maningham, TO and Dwane Bowe. so wut to do?