It's a great age, but any age is great really!
We didn't take our girls until they were 3 and 5, and once we did it, we wished we hadn't waited so long.
We have gone annually since then (girls are now 8 and 11) and we also have a 9 month old son, who has already been twice (once was in the womb, lol).
There is no bad time to go, IMHO!