There are three resorts at Disney World to where the monorail goes: Grand Floridian, Contemporary, and Polynesian.
The monorail does not go to every park and every resort at Disney World. There are a select number of resorts and two theme parks to where the monorail goes. The only resorts to which the monorail goes are Magic Kingdom and Epcot.
Anyone can ride the monorail for free, and we’ve been known to ride just because the kids wanted to ride. If you can, try to ride in the first car behind the pilot. We’ve ridden in the first car behind the pilot when a train pilot happend to be on board, and he handed out special “you-rode-with-a-pilot” sticker. (Up until 2009, guests could ask to ride in the very front of the monorail, but after an accident with a monorail train, Disney stopped allowing guests to ride up front.)
All the other resorts can be accessed by the Disney World free bus transportation that goes all around Disney property.
Thanks to my friend, Laurin, for this question.
photo credit: angie lynch

One of my favorite things to do is to ride the monorail to Epcot and then right back to the Ticket and Transportation center. It is nice and relaxing.