We did a Legoland/Clearwater Marine Aquarium trip for our 6 & ~10 year olds. We were at Legoland on the 28th and what a madhouse! I knew it would be crowded, but it was unreal. The news that night said that all the theme parks closed due to record crowds.
Thankfully we got the 2 kids tickets for free through Pepsi because we only got a few rides in. Lines were 90+ minutes for a short 2-3 minute ride. The food lines were almost as bad. For example, the carousel was probably the shortest line all day. It cycled 5 roatations, yet took longer to unload/reload. The CM had to inspect every rider (it's a 2 story ride) to be sure everyone had a seatbelt on, including adults. At the boat ride, they announced there would be no single riders, yet boat after boat went by with single riders!
I would not want to do the park in the summer. The bugs were awful. I believe they were Mayflies, and they were all over the Legos in Miniland USA. Everything is pretty much outdoors too, whereas at Disney, you can escape inside for many attractions. The water ski show while somewhat cute with the costumes, was not very impressive. We heard from locals that the fireworks are pretty good, and they give you glasses that make them look like Legos. However, we did not stick around to deal with the parking lot aftermath. We also wanted a real meal down the road before the restaurants started filling up.
The other real disappointment was the shopping. The selection was not very good. We bought a few park souvenirs, then headed to Downtown Disney's
Lego store on our way home. There they had a much larger selection, more space, and the biggest bonus-I could use my Lego VIP rewards to earn and redeem certificates. You can't use it at Legoland which is really dumb.
On a side note, if you've seen the movie Dolphin Tale, then check out the Clearwater Marine Aquarium. It's a small place, but they know how to manage a crowd. Normal daily attendance is 400-500 but when we were there it was 5200! They did a wonderful job spreading the crowd out by offering free trolley rides to their new Dolphin Tale exhibit in town. They also gave us free entrance to it, plus 20% in that gift shop. We got to bypass the long line to buy tickets at the aquarium and bought them at the exhibit (you can also buy them online). Once back at the aquarium, we walked right in. The staff there is amazing...friendly, informative, and very willing to talk to anyone who will listen. We ended the day with dinner at Frenchy's Rockaway Grill which is right on the beach. Our kids played in the sand while we enjoyed a sunset and quiet meal.