Our kids love legos! Especially our oldest. For his 9th birthday we decided to include a visit to Legoland on our family vacation to California. We already had planned to go to Disneyland later in the week so we didn't want to spend too much money at Legoland. Many destinations in Southern California including Sea World, the San Diego Zoo, Legoland and the Legoland hotel have a deal in October where kids are free with a paying adult. Legoland is open Thursday-Monday's during the fall months. Even if you don't visit during the fall I have found kids are free with a paying adult coupons on cereal boxes and online.
The pool has tons of foam floating bricks that our kids loved playing with.
Staying at the hotel is a little crazy with all the kids everywhere, but perfect if you have Lego obsessed kids for a night or two. There are three different themed rooms. We stayed in the adventure room. Our room had a bunk bed with trundle underneath in the kids area and a king bed in the other section.