Hm? I disagree. I think Animal Kingdom can very much be a full day park. If you really take the time to explore and enjoy all the shows and exhibits you'll find it takes at least a full day to enjoy most of it. We usually spend the least amount of time at DHS, but in August, we took time and visited shows that we had never seen. We took time to watch the street party, visited with the Streetmosphere people, did things we usually skip. We actually spent at least 3 or 4 partial days in that park.
If AK is just not your thing, and there aren't that many exhibits and rides that you'd enjoy, then you could do a half day there, but I really think this one is a morning starter. If you come later in the day, you'll miss fastpasses for Expedition Everest and maybe Kali River Rapids. Also, later in the day the Kilamanjaro Safari lines get very long. Don't forget to explore the back-story behind dinoland. I'll have to find the blog on that. Its fun when you know the back-story. Here is it...
http://land.allears.net/blogs/jackspence/2009/08/chester_and_hesters_dinorama.html
Downtown Disney was always our choice when we arrived later in the day, especially in the late fall and winter when the parks close earlier.