I have fond memories of the Los Angeles County Museum of Art (LACMA). I used to go visit it a lot with my family when I was younger. One thing I liked about it as a kid was the ability to use the space to run around, and not many exhibitions in LA are kid friendly in this way.
There were two different spaces where you could do this there. The first one is the lamp post exhibit. I remember spending a lot of time running through these lamp posts outside the main museum and using it to play hide and seek or tag with friends. The second space was on the bottom floor where there were these large curved metal structures that acted like mazes. I also used to spend a lot of time running around these trying to get lost. Although I have not been in a long time and probably would not run around like I used to, I still feel like the ability to do that made these spaces great.
Lamp Post Exhibit
One of the few run-around-able structures