What's frustrating for the leisure traveler is those convention discounts are pretty sweet, too. I had a colleague stay at the Grand Floridian for under $200/night on a convention rate a couple of years ago. Granted, Disney was offering bigger public discounts back then, too, but he went to this convention right before our first trip (so it must have been in 2011) and I was super jealous at how little he paid for his room.
I attended a conference a few years ago that was held at GF. The Convention room rate for a GF standard room was $199 a night (rack rate for the same room at the time was >$500 if I recall correctly) and was valid for some # of nights before and after as well as during the convention itself. Although work paid for the convention dates, I extended my trip at my own expense and paid for the extra nights of our stay -- I figured it would probably be the only time I could afford to stay at GF

As for Fall 2015, today I called Disney to add a room request to our Dec 2015 reservation. I also asked if there were any discounts available for our dates: nada. Still hoping a "rest of fall 2015" room only discount will come in this summer.
SW