In case you have not heard, Disney is doing a special priced ticket and/or package for 4 parks (must do one day in each park) for parts of December and into select dated of May. Check out this https://disneyworld.disney.go.com/special-offers/4-park-package/link:
Here is Disney information on dates:
Offer valid for arrivals most nights from January 3 through April 5 and April 22 through May 22, 2017. Book through March 5, 2017.
The 4-Park Magic Ticket grants you one day of admission to Magic Kingdom park, one day of admission to Epcot, one day of admission to Disney’s Animal Kingdom theme park and one day of admission to Disney’s Hollywood Studios on 4 separate days, and may not be used to enter the same park more than once. The following blockout dates apply: April 10 through April 21, 2017.