Let me take a contrary tack… if the 5GHz frequencies work interunit, then fine; but you may discover that need to resort to the 2.4 instead to penetrate all those walls, especially the exterior walls.
As far as naming the SSID’s same or different, there are issues either way. If they are all the same, you can register to one that isn’t the strongest one and not be able to force a better connection. If they are all different, then newbies and guests will have to accept three networks and type in the password three times. I usually throw my hands up by using the MT feature of being able to define virtual APs – on each machine, I have one AP with a common SSID, and one AP with a unique SSID. This lets the power user lock onto the particular AP he wants, while letting the low-information user do the “easy thing” that mostly works everywhere.