Christine,
Well if you are a coffee snob, then welcome to the land of joe! The Polynesian has by far the best coffee in all of Walt Disney World. While Kona Island (which serves a Kona blend in the lobby of the resort) closes around 8, you might consider a different java destination within the resort.
Since parking is technically for resort guests (they are wary of people trying to get around the parking charge for the Magic Kingdom), my suggestion is that you make a reservation for the
Kona Cafe. That way they will have your name in the system, and you can park there. Consider going there for coffee and dessert.
As for a recommendation, they have a few really great choices at the Kona Cafe. Most are chocolate-inspired, and for a special evening you might consider the chocolate fondue.
Finally, you should
ABSOLUTELY take in the grounds! Find out when the fireworks from the Magic Kingdom will go off and take it all in from the beach, where they pipe in the park's soundtrack. It will make for a really great evening!
Have a magical (and delicious) vacation!