I didn't read the other responses. The Polynesian is our FAVORITE and we have stayed there at least 8 times since daughter was 2 (she is almost 16 now). Our favorite times were staying in the Conceirge facing MK for nightly fireworks.
The Luau and character breakfast at O'Hana at Polynesian are great too.
You don't need a car, the monorail line is right there at the hotel. THe beautiful thing about MK is that you can take the boat taxi or monorail and the boat taxi ONLY goes to Polynesian and Grand Floridian from MK. It is a quick way to run back to the hotel for a nap, etc.
We always flew into Orlando and took a private cab to the Polynesian. It is about $80 roundtrip. Yes, there is a free shuttle to the resorts but you don't know how many people will be trying to get one, how long it will take to get to your hotel, etc. We preferred the private cab and be at the hotel within an hour.
Everything is easy access from Polynesian. You can walk (short walk) to the main ferry and monorail terminals. The buses for other parks have routine stops and little waiting.
Enjoy your trip! You picked a great hotel!!