I would take them when the youngest one is tall enough to go on the rides, and then they can do it together with out one standing on the sidelines, PS your never to old to go to disneyland

between ages 5 and 12 i’d say. 5 because theyre into the characters and stuff, but 12 because of the pre-teen factor. hannah montana and whatnot.

I’d say do it when they are 9 and 12, so they will be old enough to remeber it all and appreciate all it has to offer, while they are still young and worry free.

My suggestion would be DisneyWorld, rather than Disneyland. And when the youngest is between 5 and 8 would be a good time to go. Make sure you do some research before you go, as there is SO MUCH to see and do. There’s a book called "DisneyWorld With Kids" or something like that [check your library or buy a copy, so you can mark it up and keep it], and also lots of websites where past guests can give you lots of tips.