We went to BG last Jan when our 2 DS were nearly 4 and 18 months. They loved it, especially all the animals. Our eldest loved the rhino rally - he was just tall enough. They also liked the train and the gorillas. The Land of the Dragons bit was good too, but we only found that late on, so that must be an indication there was plenty to do.
BG is much less frenetic and calmer than other parks, and we seemed to go nowhere near the thrill rides at all. A good day for a different pace.
Having said all that, we did intend to go back, but couldn't be bothered to drive. When they wanted to see animals again we went back to AK.