Going to the MK, you are best off taking the bus. If you drove, you would have to park in the main lot, catch a tram to the TTC, then either the monorail or the ferry to the MK.
In the past, I strongly agreed with OKW Lover's suggestion; now, I only mildly agree with it...
During our stay at POR last month (June-06), we visited the MK using our car and using the bus. Our experience was that the car was quicker or just as quick and no less convenient than the bus. The TTC trams (we didn't need it during one visit) run every couple of minutes and the monorail runs every couple of minutes, while the buses seem to run every 20 to 30 minutes... The bus was always full and we had to wait a couple of times for someone to load their motorized scooter and unload before we got to our stop. Riding the bus could lead to a long wait at the resort and a long wait at the park.
The TTC trams lines did back up when we left late one evening, but the bus line did as well when we left late on another evening.