Oceania

Entering the southern most continent from South America, guests would pass through a Polynesian village, where a Tailspin attraction might fit in well, or perhaps something themed to Moana, like the new walk through attraction at Epcot.  

 

This region should also feature a major thrill ride, most likely a roller coaster through a volcano, which could act as the main "weenie" of the park.   

To the east of Polynesia would be an area themed to Australia, which could have something based on The Rescuers Down Under. A building designed to look like the Sidney Opera House could hold a simulator ride that allows guests to "fly" over places in Australia like Ayers Rock, the Great Barrier Reef, and the Blue Mountains.  This attraction could use Soarin's ride system or it could be more like DisneySea's Stormrider or the new Pandora ride at Animal Kingdom.  A replica of the Harbor Bridge could connect Oceania to Africa.  An attraction based on Finding Nemo would be a natural for this location as well. 

To the far south of Oceania could be an Antarctica themed attraction, or, more likely, Antarctica could be represented by a diorama on the train.  

Parades and Night time spectaculars

Parades are popular at Disney parks, but I don't see one working in my proposed third park - the themes and the layout don't really support parades.  Instead, the park should hold water pageants based on barges in its central lake.  Tokyo's DisneySea does this in its Mediterranean Harbor, and it seems to work pretty well. 

At night, the central lake could host a fireworks show like Epcot's Illuminations, or something using multiple barges combined with fireworks and other effects.  

 In any event, each of the six continents should have tiered viewing areas surrounding the central lagoon.  

Hotels

One of the great benefits of building a third park would be the opportunity for Disney to construct new hotels that would be able to charge high rates due to their proximity to the new park.  If they could acquire enough of the adjacent property to the Strawberry Field, I could see them adding three or four hotels.  Besides adding revenue, these hotels, if properly themed, could act as buffers to the outside world. 

I'd love to see a Norwegian/northern Europe themed hotel straddling over the entrance to the park the way the Mira Costa in at the front of Tokyo's DisneySea.  The western wing could have English architectural features, while the eastern could be Polish or Russian.

Alternately, they could put a English or North American themed hotel in the northwest corner, and a Russian or Chinese themed hotel in the northeast corner.

In the southwestern corner, they could build a hotel that resembled either the Polynesian Resort at Disneyworld, or the Aulani in Hawaii.  Or it could be a mismash of Polynesian and Latin American influences, perhaps called the Explorer's Lodge.

A hotel similar to WDW's Animal Kingdom Lodge would be ideal for the southeast corner. 

 

Hong Kong

I'd love to see this park layout used as a second park in Hong Kong.  Of course at Hong Kong Disneyland the entrance plaza is located slightly north of east, and Fantasyland is located slightly south of west, so a second park in Hong Kong should have it's entry slightly north of west.  I'd like to see the layout of my park stay roughly the same but shift the entrance to North America.  The entrance street for the park should complement the Main Street of the Disneyland next door, so it could be a colonial theme or maybe modern New York, or perhaps the 1920's LA of California Adventure in Anaheim.   

Another tweak that would make sense with the different entrance location would be to make the size of the mountain attraction in Oceania slightly smaller, and the size of the mountain attraction in Asia slightly larger, so that they act as twin "weenies", one on either side of Africa, which in this layout would be the area farthest away from the entrance.