I think you're going to need one day on your trip to sleep in. I remember the summer my cousins came out from Texas. We were in the 13-15 age range. We were on the go everyday, going to different theme parks. By the time we went to Marineland (I'm dating myself) we were fallling asleep during the shows. My dad was so mad at us (dang it - have fun! lol), but it taught me to be sure to have rest time.
Depending on the time of year you go, it's always a good idea to get somewhere right when it opens.
Having said that, you might be able to tailor your visits so that you can sleep in or go to bed early
Disneyland -- This is an all-day event -- you should be there open to close
Disney Adventure Park -- Usually opens at 10am & closes at 6pm or 8pm. I recommend making this a short day & just hitting the highlights
Seaworld - I think it's open 10-5 - It'll take 1.5-2 hours to get there & return, so keep that in mind
Universal -- this is about a 3/4 day park. Even though it's better to arrive early, you might want to sleep in, and invest in the front-of-the-line passes to maximize your time without wearing you out
Knotts Berry Farm - Again, probably a 3/4 day. Sleep in, and just enjoy the park until you're ready to go home
Six Flags Magic Mountain -- This is going to take you awhile to get there -- Only open on the weekends during non-peak season, so check the hours here.
Have a great time!