the Polynesian is close to POR only if you have a car, or you want to take a taxi.
It is possible that if you drive to the Polynesian you will be given a three hour parking pass, which would mean you can't leave your car there and go to a park for the day. Apparently they don't always give out the passes but sometimes they do, when it is busy and they are trying to keep parking available for Polynesian guests. If you are going to the Magic Kingdom for the day, park in the MK parking lot and walk to the Polynesian from TTC (or you could take the monorail, but it's only one stop and it's close).
If you are planning to use Disney transportation exclusively, and you are going to the Polynesian from a park, the closest by far is Magic Kingdom, to or from which you would take the monorail or the boat.
If you are going to Kona from your resort, you will need to do a transportation switch at a theme park or Downtown Disney, as you can't take Disney transportation directly between resorts. If the parks are all open, the best bet is to take the bus from POR to the Magic Kingdom and switch to the monorail or boat.
If the MK is closed when you head home and the transportation is not running, you will have to switch at either a park or DTD. DTD takes the longest to get to, although you do have the added option of taking a boat from DTD to POR, assuming it is not so late that the boat is no longer running.
If you want to go to the Polynesian from a park other than the Magic Kingdom here are the options:
Epcot: Take the monorail. You will need to either switch monorail lines at the TTC, or you can disembark at the TTC and walk to the Polynesian.
DHS: Bus to the Polynesian (will stop at the Contemporary first). Or, bus to TTC, and walk to the Polynesian.
AK; Bus to the Polynesian (may stop at Blizzard Beach, and will stop at the Contemporary first). Or, bus to TTC, and walk to the Polynesian.
