How much flow, and where?

[JoelF]

For the past while I have started playing with where the flow in my tank is directed. In my 90G I have 2 802 powerheads, with pre filters, a 402, and quiet one main pump that flows into the tank in 2 seperate fanned outputs. My question is, do you try to get a nice even flow at the top, bottom, some top some bottom?? Different heights? Too many powerheads, not enough?? Kinda a broad question but any help would, well, help.

(had to try a face)