Hi Debbie,
Yes we have been on Aug 31 and to be honest, the park was busy, but the trade off was that the park was open until late, great weather (which I hope you get too) and a good atmosphere. (We found many different nationalities there at this time).
Use Fastpass and try to get to the park for opening - in the evening explore Adventureland, it is a lovely section of the park at night. We found the line wasn't too bad for Pirates at night, and it's the only time the Swiss Family Robinson Tree is worthwhile for the views!
Pick your spot for the night-time parade in plenty of time and then your spot for the fireworks. We made our way up to the Castle and the garden centrepiece in front of the castle and this area got absolutely chock-a-block!! There were feet in the flowerbeds from people perched on the little railings around the flowers (can you imagine that in WDW??!! I am sure they must redo that garden bed every night after park close!!), but we just kept smiling and enjoying ourselves and ultimately the fireworks once they began!
