Avoid Weekends. Mondays and Tuesdays are the slowest days of the week during the summer. Like others have said, it will be crowded, but nothing compared to a Disney or Universal/IOA crowded. It would be easiest to do two days at Seaworld and split your days in half. It's easier to do two half days instead of a park open to park close especially in the summer months. Splitting your visit into two half days will allow for less rush and more time to enjoy the park. There are special night time only shows performed during the summer season. Shows like Shamu Rocks, And Sealions tonight. There is also a fireworks show. All night shows are different than day shows. Like I said, I would do 2 days at the park. Day one from 9:00am (park opening) until 4 or 5. That will allow you to see day shows, rides and exhibits. The next day do like 3:00pm until park close so you can ride any rides or see any exhibits you may have missed the first day or really enjoyed and want to do again, and you can also catch the night time shows on the 2nd day.