When I go with my 5 and 1 year old, we always do the same rides. Haunted Mansion, Pirates of the Caribbean, Small World, Jungle Cruise, Tarzan's Tree House, Astro Blasters, Carousel, and any Fantasy Land ride that doesn't have a horrible wait. There are changing tables and kid sized restrooms on Main Street at the Baby Care center near the corn dog cart. Download the Disneyland app too, it'll be a huge help for finding rides with no height requirement.
My daughter went on her 5th bday and her younger sister was about two. We went on its a small world & the teacups. With small ones its kinda rough with the long lines. They make you park your stroller way on the side before standing in line , i actually couldnt find mine for a good 15 mins cause someone moved it! And make sure you spot out bathrooms before hand i had waiting in like for the dumbo ride and got to front and my daughter had to pee 😒 35+ mins gone lol so make game plan 100% before. Kids loved the toon town with the play houses:)
There are a few that would work for an infant. Small World, Storybook, Casey's Train, Tom Sawyers Island, Haunted Mansion (too young to be scared, but the 4 year old may get scared), the train going around the park would be a few good ones.
Try carousel is about the safest
There are many things to ride on, but some might be scary for the 4 year old, Snow White, Pinocchio. Small World is a good one for everyone.
I believe most of the Fantasyland rides, the train, autopia, buzz Lightyear, Jungle cruise, Mark twain, etc etc
There are a lot of rides you can get on while holding your baby. My girlfriend took our son when he was a couple months old. Some include Winnie the Pooh, Small World, Jungle Cruise and a couple others
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