Looks like my 9yo daughter really wants a switch for Christmas. I am getting the bundle with Mario Cart so that will be on there. Any other good games for that age, especially for offline use (planes/roadtrips)? Only real game she plays are web based educational ones from school and Roblox. The last game I bough was probably Rockband for my Wii about 15 years ago so I'm out of the loop (I still kick ass on the guitar though).

My boys loved Super Mario Odyssey:
https://www.gamestop.com/video-games/nintendo-switch/products/super-mario-odyssey---nintendo-switch/147668.html?gad_source=1

There are a lot of Super Mario games for the Switch. This one is an older one but is the game they have played the most out of any of them.

The Bluey game is fun.

She could probably handle Animal Crossing. The Just Dance games are fun for that age, but obviously not something you can do in the car.

Another vote for Mario Odyssey.

I would also suggest the Kirby & Yoshi titles for a 9 year old.

Odyssey, and Breath of the Wild

The newest Mario game for Switch is Super Mario Wonder. It's a 2D side scroller that's tons of fun. My daughter (also 9) and I love playing together.