3 years ago, I drove down from DL to Legoland, at the time, my kids were 9 and 12. Since it was my DD's bday, they gave her a Bday button. My kids thought it was funny that we got a $2 bill for change when paying the parking fee.
We went the end of August, and since the park did not open until 10am, I left DL around 8:30am, to avoid some traffic (it was a Tuesday) and we arrived before opening. We did the park all day, and then about 1/2 hour before closing, we spent the rest of our visit in the aquarium. It is a neat place. It is small, and somewhat dark, but everything is low for the kids to see. My favorite was sitting (ok laying on the benches) in the room with fish on all the walls and ceiling. So relaxing. I also, closed the place, as I wanted to stay until after the closing (which was 6pm) to again, help avoid traffic. It was about an hour down, and a little longer on the way back. My kids liked how wide the highway was, and the DL and Legoland exits are not far from the highway. We used the HOV lanes and even the HOV exit to get back to DL. I didn't mind the drive.