Not anywhere near WDW.
Seriously, that's a good question. I know exactly what you mean - a place that isn't crawling with children running up and down the halls, splashing in the pool, crying babies etc. Unfortunately, I don't have any to recommend. Maybe someone else can help.
My guess would be that the farther you can get from Disney, the better your chances will be. There are some nice hotels in the city of Orlando that might fit the need. And its always been my experience when traveling in other cities that the pricier the hotel, the less likely there is to be a lot of kids since young families are usually staying at less expensive places. Another place to look if you don't mind a drive to Disney is along the Gulf Coast.
Good luck.
Steve
P.S. I just read another post saying the Celebration Hotel is very nice and doesn't attract many families so check that out.