Like snake asked, what size is your tank, and how far is it to the sump? The amount of water you want to move will determine the size of plumbing.
Unlike snake suggested, I like to keep things simple, compact, so I'd recommend dual overflows (one on each end of the back) and a single return. I suggest using slightly larger bulkhead and tubing than needed. Larger drains will allow water to cling to the walls, which makes it very silent. It also prevents siphoning, which is loud and annoying. Elbows inside and outside the overflow bulkheads take up considerably less space than adding an overflow box (whether inside or outside the tank). From what I've been able to find, bean animal and herbie methods can be tricky to adjust, and they're never completely silent. Just another option...