My 4- and 6-year-old had a blast there. Most of rides are quite mild, so tweens and up may not enjoy them much. Also, most rides are interactive - allows kids to control some functions, so it was cool.

BUY YOUR TICKETS at an AAA location. I bought 2-day tickets from Legoland's website and canceled them because tickets from AAA were $50 cheaper total. It paid for the AAA basic membership!

My favorite place is near boat dock, where there are always music and some activities. King St and Union St mark the center of Old Town. From there, you can check out Old Torpedo Factory, which houses artists and their works, and thus could be too much for little kids. There is boat dock, food court, the Charter House restaurant, a cruise boat, and Founders Park. One hour should be plenty, and there are plenty of park benches.
Parking could be tough, especially during dinner rush hour.

Place for kids of all ages to explore many things. Avoid weekends before 2PM. Closes at 5PM, but if you get there at 3-ish, there are a lot less people. Also, if you going to visit multiple times, it makes a sense to get membership.