I love Disney and went to
Disneyland throughout my pregnancy (including at 39 weeks). However, I only live 1 hour from Disneyland (without traffic). I think it will make a definite difference if you need to fly at 32 weeks vs 36 weeks. At 32 weeks, I'd still go, but at 36 weeks, I might not want to make the flight (some airlines won't even let you fly during the last 4 weeks -- I think, but I'm not sure).
Here are some of the things I can think of:
Wear super comfortable shoes! You may even need to buy a new (bigger pair). My feet have grown a half size with each pregnancy (permanently unfortunately)
Wear comfy and breathable clothes. It is hot and muggy in Florida in summer. Dress lightly.
Drink lots and lots of water. (And go to the bathroom lots and lots, by now you no longer have a bladder and you're drinking extra water. For me, this was the only real nuisance of being pregnant at the park. But, I would have been visiting my own bathroom all the time anyhow)
Make sure you have been active and walking a lot your entire pregnancy. It is fine to walk around the park all day when you are used to it. Your 8th month of pregnancy is not the time to try increasing your exercise routine, your body will make you pay for it and it could be distressing for your baby. In my (non-medical) opinion, suddenly increasing your walking/exercise to a few long days in a row is way to risky. I walk all day long at work and I have always been partial to ridiculously long walks (and I frequent Disneyland all the time), so I was very comfortable walking around for long days.
Don't plan too much in the day. You'll be walking slower and may want more frequent breaks.
Most important -- have fun!