I have ~4000 square feet on two levels, and I am trying to place the router and satellite units in the best location.  I know the center of the house is ideal, but my house is configured in a way that there is no furniture in the middle of the house.  My question is, will I lose signal strength if I mount the router up high on a 9ft interior wall in the center of the house, or would I be better off putting it down at table-top level somewhere less center in the house?  Does anyone who has mounted their devices up high have any thoughts or recommendations?  Does it make a big difference? I do plan to hardwire both units for maximum thoughput.

Thanks!