Personally, I think AK is an underrated park, and you could easily spend a full day or more there, but, if you are willing to miss the AK afternoon parade, I agree with Disnee Dad that you can more or less get through AK by mid-afternoon.
If you're staying on-site, use the Magic Hour. Go direct to the Safari ride at opening, use Fastpass as necessary for Dinosaur, It's Tough to be a Bug and Kali River Rapids, skip Rafiki's Planet Watch (enjoyable and educational, but a time-eater in relation to the attractions there). See the Lion King show, skip Tarzan if you are running low on time.
You could go to the Studios on the evening of your AK visit. See Fantasmic (perhaps use the dinner package to cut you wait in line) and whatever else you can squeeze in (keep FastPass in mind).
You have to hit the Studios during daytime hours to make the shows. Go for Magic Hour if you can--go direct to Tower of Terror and Rock 'N Roller Coaster, get FastPass for an early show of Little Mermaid (small capacity theater). Schedule around showtimes for Indiana Jones (Fastpass available here, but it's a huge theater and usually not necessary to use Fastpass) and Beauty and the Beast (and Playhouse Disney if you have young kids), and the afternoon parade if you desire. Use Fastpass as necessary for Star Tours, Muppet Vision 3-D and Millionaire (and Tower of Terror and Rock 'N Roller Coaster). If you still have energy left after all this, since you will already have seen Fantasmic, hop over to Epcot's World Showcase for dinner and Illuminations.