We stayed at the Woodrun over the 4th of July in 2003 during an unseasonably warm spell with temps in the 90's. The Woodrun has no air conditioning, but I think those were pretty unusual temps, no air would not stop me from going back.
You said you have three teen boys, do they ski or snow board? There was still skiing in July, in fact the boys could walk from the unit to catch the lift in the upper village. Another teenage boy thing that might appeal was mountain biking, where they take a lift up and bike down one of the lower slopes that had no snow.
The pool is on the small side, but there is a popular lake close by that you can bike to that also had swimming. Hiking, rafting, biking, shopping, fine dining among other options.
There is tons of stuff to do in Whistler in the summer, I think you will have a hard time packing everything in.
Have a wonderful trip.
Gayle