Nice!
Anywhere in the Valley is going to be a great place for the kids. Mirror Lake, Lower Yosemite Falls, Vernal Falls if they're up for it, explore the meadows (maybe even see a bear), swim in the river, Museums, bop around on some boulders......
Tuolumne Meadows is another great destination...Lembert and Pothole Domes, running around Olmstead Point and Tenaya Lake going to or from...
Glacier Point for sure.
It's like a big playground for all ages. It's basically whatever you think they can handle and as far as their little legs and sense of exploration can take them. Get them a couple little day packs and a cool water bottle and they'll be even more stoked. Check out this website for more info and ideas:
https://www.nps.gov/yose/planyourvisit/things2do.htmWith traffic: Weekends might be a little heavy, but getting to the park early usually helps with that and parking. The shuttle system in the Valley is an integral part of making getting around to almost anywhere you want to go much, much easier. Definitely use it to your advantage.
If you have more questions, ask. If not, have a great time!