I agree with everyone, 1 day should be fine, unless the park is just JAM packed. Get a fast pass for the Safari or Everest as soon as you arrive, and get in the line for the other one. They are the longest waits usually. Also, the Nemo show is awesome and can fill up on busy days, so be sure to get there a few minutes earlier than show time to get seats.
We often skip Rafiki's, I know some people LOVE it, but it's so similar to what is at our zoo here I see it as more of a time consumer. We love the walking trails, and save Kali rapids for last unless it's a hot day!