With some careful planning, you can do and see everything in one day if the park is open 9-9 or more (which it is in the summer). When you get in the park, grab a park guide and check the showtimes - see the earliest show on the schedule. Our plans had us doing one show every hour and seeing the nearby attractions in between the shows. Ride the rides either first thing in the morning, or at lunchtime, at the same time as the afternoon dolphin show. Then, everyone will either be eating or at the show. This worked perfectly for us.
By 2pm, we'd seen everything on the left side of the map. Then we checked out the waterfront and made it over to the bayside theater, wild arctic, the shamu show, and the clydesdales, then back to Shamu Rocks America at night. It was a full day, but we didn't miss anything.
I especially recommend Pets Ahoy. It's a really cute show.
Tara