If you plan on going again (not once in a life time so we want our child to remember it) then I think they'd enjoy going at about 2. It's a very magical age.
I've taken our DDs ages 1, 2, 3, 4, 5 and so on...
age 1 was ok. I'd do it again but she basically sat in the stroller and took it all in. She did do rides but was VERY afraid of fireworks and characters. Each year she got better at those two things...
Age 2 was much better. She could talk and walk and loved the rides more. She enjoyed the face characters. Still didn't like the fireworks. She was in amazement of everything! She LOVED the parades this year.
Age 3 and 4 and even 5 were very magical and wonderful trips. She was not afraid of the characters, Fantasmic, fireworks. Could go on many many rides loved the parades, could walk and talk and have a grand old time!
IMHO, if I were to do it all over again, probably age 2 or 3...although 2 is FREE and 3 isn't so probably 2 1/2!
