When we had about a 10 hour layover in T5 in mid-July, our group of three took two cabanas in the Concorde room. I think there were about 5 rooms total. We were not given a time limit. They are assigned on an availability, first come first served basis. I think we could have gotten three rooms if we had asked. It all depends on luck. I believe we were there on a Sunday, don't know if that made a difference.

Based on my experience, I would check with the departure Concorde room first even though it is airside. Someone else would have to tell you if there are cabanas in the arrivals area, but I think probably not.

Good luck!

nonutrix