How Much Flow?

I'm coming from the saltwater reef hobby where it was all about water flow/movement, and lots of it. How much flow do you have in a planted tank? I was planning on having my return water go through a four way valve that rotates the output out of four separate outlets, one at each corner of the tank, providing random currents. Would something like this also be benificial to the plants as well? Do you guys use powerheads as well to move the water around? Please give some examples of pump sizes versus tank size, etc. THanks in advance.