We had our reception at the American Adventure at the World showcase in Epcot.
(ideal for less than 40 guests). It was wonderful. At 9pm we went outside to a viewing area to watch the fireworks and then carried on until about 11pm.
We booked extra time thinking we might be there until 1am, and paid $200 per hour, but we were so tired we all went back to the hotel at 11.
A theme park location is great. The magic Kingdom would have been first choice but sadly I am not that flush. Epcot is brilliant, as you can have the fireworks too!