Hi there,
The Monorail runs from the Polynesian Resort, Grand Floridian and Contemporary Resort to the ticket and transportation center in one big loop. There is a train that runs from the ticket and transportation center that goes round trip to EPCOT.
It would be easy to do this, but where would you park your car?? You would have to find out if you could leave your car at the Polynesian. I know they have a limit on how long you can leave your car there. I guess it wouldn't be a big deal in the evening, plus you would have reservation at the kids club. If you didn't have a car, the only bad thing is you would need to take a bus from the monorail hotel, to downtown disney and then to CSR. This is very time consuming, and the buses from the monorail hotels to downtown disney can sometimes be a long wait. I remember waiting at the Grand Floridan for several hours waiting for the bus once. It didn't come till about 11pm. We were so upset because our kids were very tired. They kept saying the bus was on its way.