My sister in-law took her sons to Sesame Place when they were young and she told me our neices (who were 5 and 6 and the time) had way more fun than her 1 yr old son did. Partly because the young ones were frightened of the large Sesame characters roaming the park and of the loud shows.
Perhaps you should consider taking your son to Land of Make Believe: http://www.lomb.com/Attractions.html. I plan on going this weekend with my 3 yr old again. The whole park is geared towards little ones. It's very family oriented without all the loud hubbub of larger theme parks. They have a large wading pool for very young children, petting zoo, train ride that goes all through the park, free parking and inexpensive entrance fees, and good food. Maybe seeing how your son reacts to something more low-key before taking him to a large theme park is a better option while he's so young.
Have a great summer!