Harvey and Bill,
The attached .pdf file is a copy of page 207 of my owner's manual showing that the GCWR of my Highlander is 8495# and that it has a 3500# tow rating (please forgive their typo on the engine model number-- they DO know the difference at Toyota between a 6 and a 4 cylinder engine). The picture attached shows my driver's side door placard that identifies a GVWR of 4985.
4985 GVWR + 3500 Tow Rating= 8495 GCWR
All of the Toyota Owners Manual towing calcs I've worked through on this message board so far are conceptually similar (Sienna's, Tacomas, Tundras, Rav-4's 4-Runners, etc.), where the GVWR + the tow rating = the GCWR (but Toyota could change the way they report tow capacity someday for one/some/all of the models and I would never know, of course). "Do not exceed any Weight Ratings and follow all instructions in your Owner's Manual..." sounds good to me.
When I posted earlier on this thread, I'd found a Toyota towing information resource which I wish I had linked for you, because I can't find it right now. But, here's the 2009 Venza ebrochure:
http://www.toyotacertified.com/ebrochures/09_venza.pdf
Hope this helps.