Greetings, Mariko!
Welcome to the Disney Parks Moms Panel, and thanks so much for your great question. Disneyland Resort has something for everyone at every age, so I know that everyone in your family is going to have a magical and memorable vacation.
You can conveniently view all
attractions at the Disneyland Resort online or on the
Disneyland app. You can sort them by height requirement and also by if they offer Disney FASTPASS service. While many attractions for little ones do not offer FASTPASS, we still have used it quite a bit with our preschooler. Some of my son's favorite attractions offering FASTPASS are Buzz Lightyear Astro Blasters, "it's a small world," Roger Rabbit's Car Toon Spin, Toy Story Midway Mania, and Haunted Mansion. If your children are 40" in height then you will have even more options to use this service.
If you are on a budget but still want to make use of the Disney MaxPass feature to make digital Disney FASTPASS selections, I recommend trying it out one day of your stay. Since you can add this feature easily via the Disneyland app each morning, you aren't obligated to pay for this service every day of your stay if you are unsure if you will use it. We have often used Disney MaxPass on some days and decided to pass on others depending on what our plans are. Remember that you can still always get complimentary FASTPASSES in person at FASTPASS distribution kiosks near attractions offering this service. Disney MaxPass just gives the added convenience of using your mobile device to do this.
I hope this helps, and please return if you have any other questions. Have a Zip-a-Dee-Doo-Dah day!
-Jennifer