Most organizations strive to keep the ambiant temperature at 70 degrees. The flow of air is very important if you wish to acheive this goal. One way of making sure that your DC does not get many hot spots is to make sure that you have the exhaust side of your cabients face each other. This way you will not be exhausting hot air into the intake side of your cabinets. This will also create an air flow to the return portion of your ac units.
That idea hadn't occured to me jcooper, on more than one occassion I have thought how would I cool a datacenter if I ran one. Something I would try was blasting old air into the computers themselves.