I attended a professional convention which met at Disney World. We ended up booking a condo a couple of miles from Disney World itself. It was cheaper but I can't remember the name of the place. It was about a 5 minute drive.
We got discount tickets by attending a presentation at a time share resort. The offered it to us when we picked up our rental car at the airport. Got breakfast and spent an hour repeating to the salesman that we weren't interested in a time share and saved some $$.
Three days would be way too much for me. I could barely stomach one day of it. Took my 8 yr old daughter to Disneyland 2 yrs ago and 1 day was fine for her.
We drove to St. Augustine and spent a day doing historical visits and another day at Cocoa Beach rather than spend more than one day at Disney.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13