Worth riding ..... If the wait is <20 min
A lot of guests wait unnecessarily as they think they need to stand in the parks' first line.
I always ride Spaceship Earth, but I keep looking at wait times so I don't waste time in the too-common 30+ min waits of the FP+ era.
For the OP's specific scenario... The 11y/o should get some enjoyment from the interactive part in the car, and the 9mo is allowed...and any ride that the whole family can do, is a good ride!