Yep. If you're staying at the resort, you get a parking pass that you have to display. Not sure how long you could go without that before they would notice, and not sure what the penalty would be.
The parking for the MK is at the Ticket and Transportation Center. If you park there and get on the resort monorail (NOT the express to the MK!), the GF will be the second stop -- not bad at all. You could then take the monorail or the boat (from the GF) over to the MK. (And then monorail or ferry boat back to the TTC for your car later.) (The GF boat is technically for resort guests (GF and Poly), but they neither ask nor check, or didn't when we were there one month ago (we were at the Poly).)
For the Contemporary, it might be easier to park twice -- once at the hotel, and then again at the TTC after breakfast. The resort monorail route is a one-way loop -- GF, MK, Contemporary, TTC, Poly, repeat. You'd end up doing two full loops by the end of the day if you were to start at the TTC and take the monorail around.
mommy to three boys: A, 3/04
and identical twins B and D, arrived 9/08