Hi
With late park openings you might fit a visit into the studios, depending on what you want to achieve with your day. I think the most of your time will probably be in the main park, but the parks are very close together, about 5 minutes walk, so you can park hop if you wish.
I'd start with the main park. If Big Thunder Mountain is a must ( and I think it should be

) take a quick route there via Liberty Arcade, which is to the left of Main St. Once through the arcade turn immediately left and you'll be in Frontierland - you will almost certainly need fast pass for this. Whilst there you could visit Phantom Manor.
I'd then head into Adventureland to visit Pirates, Indiana Jones and a walk around skull rock are to see Captain Hooks ship. If it;s a nice day, a visit to Swiss Family Robinson Tree House would be nice too.
From Pirates, follow the path into Fantasyland where you'll see Peter Pan (fast pass will definitely be required) Alice's maze (not to be missed), and the usual FL rides. You might also want to visit Mickey in his new purpose built meeting place, or some Princess'? Take a rest on the storyboats (top left of Fantasyland) and then wander past Small world into Discoveryland.
Here you'll find Buzz, Start tours, Space Mountain and a nice walk though of Nautulis. The Videopolis is a quick place to stop off for some counter service food/drink and you can usually see vintage Mickey cartoons there too
From Discoveryland pass Buzz and you'll be at Central Plaza, the main hub of the park. Now take a look at the castle.....

You can visit inside the castle and go upstairs for the story of Sleeping Beauty and a lovely view over Fantasyland. Downstairs, which you can enter either from outside or the glass gift shop, you can meet the Dragon..
If you have time, pop over to the studios or enjoy a luxury table service meal at Walts in Main St. If you're there until park closing time, make sure you stay to see Dreams....unmissable
I've probably missed loads of things that others will think of, but for a single day I think you'll manage the main attractions.
Hope this helps a bit
