We just went over Spring Break for the first time with my 7 1/2 year and just-turned-five year old. We went for 3 days and figured out the timing for us - get there 30 minutes before gates open and your parking won't be terrible (still a long walk, but doable). The kids had energy each day for 1 show, 1 other activity (feeding dolphins, walk through aquarium/shark house, penguin house), and playtime at the huge playground and splash area. The playground can be a little stressful because it is huge and it is easy to lose sight of your child - you have to either follow your child through or have a kid you know will be willing and able to come back to you - may not work with a 4 year old. There is a large sand play area underneath the play area that is contained though. Very little seating or shade for parents here, unfortunately. For shows -get there 30 minutes to an hour ahead of the show and wait outside the gate - have snacks and maybe some books or small games ready for the wait time. You can take snacks in, but nothing in glass and they say the snacks have to be individually wrapped (not just a huge box of goldfish, I guess) and for some reason the web site says you can not take in sandwiches (?!). We took boxes of individually wrapped granola bars, fruit snacks, and peanut butter cracker sandwiches. For srinks I took empty sports bottles (so we didn't have to carry heavy liquids all day)and those crystal lite flavor packets you add to bottles of water - then you can just fill up at a water fountain but not necessarily have to drink water, but not pay the insane park drink prices. We bought no food or drinks while we were there. For tickets, I don't know if they might still be offering the Fun Pass - pay for a day, get unlimited visits for the rest of the season. The difference between this and a season pass is it does not cover parking or get you a discount at concessions or gift shops. So what we did was get one season pass for me - that got us the free parking ($15 a day other wise) and discounts on the few items we bought in the park - everybody else got a Fun Pass which was about $30 less (the cost of 2 days' parking - we went for three, so got one free day of parking plus 10% off in the gift shop). TAKE SUNSCREEN! We didn't and paid way too much in the gift shop for some after I got sunburned. Let's see.... oh, the 4-D pirate movie is funny, but my kids were stressed the whole time because they thought water would shoot out of the nozzles in the seat in front of us (they warn you that you might get wet) - the nozzles only shot a little air, and we only got a little sprinkled from above. But my 5 year old was so worried through the whole show he enjoyed none of it. He found some of the 3-D a little nerve-wracking too (mainly when it looked like the cannon was shooting at us).
Okay, too much info? (: Hope some of it helped! Oh, there is a McDonald's right near the entrance too, but no playland there. Rudy's Barbecue is at the same intersection - good stuff!
Good luck! Have a blast!!!!!