CruiseAir units are quite common in bus conversions. Look at the roof and if there are no AC units up there you can bank on the coach having three or four CruiseAirs. Bruce's coach is an exception and there may be a few others. I prefer CruiseAirs and I'm sure there are folks who like roof air units. Both will cool a stationary coach when functioning properly. The advantage to roof air is, like Jon says, they will cool better while the coach is traveling. But, a bus with Prevost OTR air is the best option for summer travel.