I'm new to this, so this may be old news to you guys, but I thought I'd share anyway. If you have little ones who are too short (or even bigger kids who are a little too nervous) to ride the 3 mountains, you can get special "future ____" certificates (suitable for framing) for free at these rides in the Magic Kingdom. For example, at Splash Mountain, they will give you a Splash Mountaineer certificate, which shows brer fox and brer bear and brer rabbit on it, and states that the bearer of the certificate is entitled to go to the front of the line when he or she is big enough.
I had never heard of them until we discovered these a few years ago when my then 5 year old son found out he was just a tad too short for Space Mountain. He started to bawl his eyes out, the cast member asked us to wat a second, opened up her kiosk, and produced the magic certificate, signed by the big mouse himself, and filled in my son's name on it These certificates are really nice, and make great souveniers -- we've never been able to bring ourselves to part with on by using it as a front-of-the-line pass. But you do have to ask the CM for it, they don't seem to just volunteer them!