You should look at the pool view view pictures over on the Aulani Villas and Views thread. That will give you a good idea of how much of the ocean you can see from the 4 & 5th floor.
5th floor is the highest floor in the poolview category.
The rooms with pics are all linked in the first post so you can just click to see view pics:
http://www.disboards.com/showthread.php?t=2907389