Thanks for all of your input.  As has been stated by many, it's hard to predict way out into the future.  But I would say that our most likely times to visit right now would be anytime Nov-Feb, or May.  I wouldn't completely rule out Sep, Oct, March, or April, but those would be far less likely.  And as I said earlier, I have no desire to go June-August; with the summer heat combined with summer crowds.  It seems to me based on that (assuming I understand UY correctly) that September would be the best option for me.