The Polynesian is within walking distance of the Transportation and Ticket Center, unless you had party members who were mobility impaired (even then they'd have to go up the monorail ramp) you wouldn't even have to use the monorail. I'd imagine that you'd have to pay the parking rate at MK, unless you have an annual pass or have already paid a parking fee at a theme park that day. But you can park at the Polynesian, although you should be aware that if you intend to go to the MK after dinner, you might be given one of those three-hour parking passes.