Would this be a good place for a three and five year old or should I wait a few years?

It would be more exciting for older kids. Suggest you wait for another couple of years

I would have to agree. Wait a few years.

I don't really remember seeing really young kids there when I went. It was mostly 7 year olds and up.

Mmmm it's a very tiresome day.

There's things for them to do and they would find it enjoyable if they are very intelligent and interested in such things, while they have things to entertain them most is geared towards adults in my opinion.