Don't you just love lots of windows in gyms! Our 2nd gym at Klein Oak has two glass doors at one end so I'm often fighting the same problem.
I'm curious as to why you are limiting yourself to ISO 3200. Some of these show considerable motion blur. I'm usually shooting at ISO 5000 with my 7D even in high school gyms. I'm usually at 6400 or above with my 1DIV. Noise at those settings is pretty easily controlled with these cameras. At least I don't find it objectionable.
I shot a league game for a friend last weekend in the 2nd gym at Aldine Nimitz. That qualifies as the worst gym I've ever shot in. I was forced to go to ISO 12,800 on my 1D4. That froze the action but I just couldn't find a white balance that worked for multiple pictures. Very frustrating.
