A lot would depend on the number of users you plan on accomodating but I would think if a car dealer would be at a minimum. Additionally a site survey would let you know exactly what you need. Having said all that, in my limited experience I would think that since this is an open area you could start with 5 APs having one right square in the center of the building and the other 4 centered in each one of the 4 quadrants. I have had really good luck with the Omni 1728 Antennas attached to the LAP1242AG-A-K9 Access Points. I am farly impressed with the coverage maps that these produce. We are also using WCS Software as a front end to the 6509 WiSM Module and have had no problems with load balance. I am assuming the the smaller stand alone appliances will produce the same results. Redundancy would probably require another AP or two which would let a failure occur without service interruption.