There have been a couple of threads on this before.
http://www.chevysuburbanclub.com/tctc/csc/PNphpBB2-viewtopic-t-26-highlight-trailer.phtml
I found some information on the newer suburban's towing limits for the past couple of years.
1/2 ton with vortec 5300: 8400 lbs (2wd), 8100 lbs (4wd)
3/4 ton with vortec 6000: 9900 lbs (2wd), 9600 lbs (4wd)
3/4 ton with vortec 8100: 12000 lbs (2wd & (4wd)
http://www.chevysuburbanclub.com/tctc/csc/PNphpBB2-viewtopic-t-26-highlight-trailer.phtml
I found some information on the newer suburban's towing limits for the past couple of years.
1/2 ton with vortec 5300: 8400 lbs (2wd), 8100 lbs (4wd)
3/4 ton with vortec 6000: 9900 lbs (2wd), 9600 lbs (4wd)
3/4 ton with vortec 8100: 12000 lbs (2wd & (4wd)