yes, you should definitely go! We just went last week and our kids are almost 3 and 1. It was a bit over the top of my youngest's head, but my 3 year old loved it. I will probably wait a couple of years until we go back, though, as it's definitely geared MOSTLY towards the 5-9 age group. That is, most of the rides have minimum height and/or age requirements, so the very young cannot enjoy it fully.
I think your kids are at the best ages to go, so you should definitely plan on a good time.
A couple things:
-go on a weekday
-arrive BY park opening. If you are staying at DLR, leave by 9am. You will arrive right at 10am.
-the park has short hours and is NOT open 7 days/week. be sure to check
www.legoland.com for current park hours.
-Legoland CLOSES when it's raining. Unlike most other parks, it can close at the last minute due to bad weather. Be sure to plan on going on a day where there is no chance of rain.
-the tickets are EXPENSIVE. Try to get them through a discounted source if at all possible. I know with AAA you can get a 15% discount at the ticket window, but there are deeper discounts if you look for them. I think the adult ticket price, at $57 is especially ridiculous, considering adults cannot even go on many of the rides.
-the park is MORE crowded in the first few hours and then as the day goes on, the lines become non existent. This is due to the large number of local parents who bring their preschoolers and toddlers for the morning and then leave around 1pm. Skip all the stuff in the front areas of the park and head back to that stuff after lunch.
-there is a new area that is water themed. It's called Pirate Shores or something like that. Bring bathing suits/water shoes for all your kids, along with towels and sunscreen! This place has some wet rides as well as full on water slides and water jet play areas. You CANNOT enter this area and leave dry, no matter how hard you try. There are lockers you can use at the front of the park to store your stuff until you need it. This area is in the back of the park.
-Make sure you check out the new Las Vegas model in Miniland. It's really cool!