The backstory on the planned trip is that we had for many years promised our granddaughter than, in lieu of getting toys for her birthday and Christmas, we were going to arrange a trip for her, anywhere in the world she wanted, with me and Grandpa, when she was 10 or 11. (The idea is that she'd be old enough to appreciate the travel, and able to do the geography research that we suggested her to do, and young enough that it would still be okay to spend a couple of weeks with us old-folks without extreme amounts of juvenile eye-rolling.)
When we were last discussing the trip idea with her, she expressed distaste for the idea of a long airplane flight. "Grandma, when I have to sit for so long in an airplane, it makes my butt flat!" After I reassured her that her butt only felt flat, but actually bounced right back post-flight, I asked if she might prefer a train trip in the US. She expressed enthusiasm--we took the CS end to end with her in the family bedroom last summer, and she handled it fine. So, I am planning something like this: Keystone from Lancaster PA to NYC, two days in New York, the Lake Shore Limited to Chicago, two or three days in Chicago, the Southwest Chief to Los Angeles, one day in LA, then on the Surfliner to San Diego, two days in SD, and flying from there to Seattle, our hometown, where she'll meet up with Mom and Dad for All Star Weekend.
So...thoughts for what I'm not thinking about? The plan is to go with a bedroom and a supplementary roomette for Grandpa, since I think the family bedroom probably won't work by next summer, since she is already nearly five feet tall. I need to book in the next couple of days, I think. What are the can't-miss-with-kids things to do in our stops? Many years ago, we did travel with her mom as a kid, but our granddaughter has a rather different personality--brash and active, rather than quiet and day-dreamy. Am I crazy to try to do this?
When we were last discussing the trip idea with her, she expressed distaste for the idea of a long airplane flight. "Grandma, when I have to sit for so long in an airplane, it makes my butt flat!" After I reassured her that her butt only felt flat, but actually bounced right back post-flight, I asked if she might prefer a train trip in the US. She expressed enthusiasm--we took the CS end to end with her in the family bedroom last summer, and she handled it fine. So, I am planning something like this: Keystone from Lancaster PA to NYC, two days in New York, the Lake Shore Limited to Chicago, two or three days in Chicago, the Southwest Chief to Los Angeles, one day in LA, then on the Surfliner to San Diego, two days in SD, and flying from there to Seattle, our hometown, where she'll meet up with Mom and Dad for All Star Weekend.
So...thoughts for what I'm not thinking about? The plan is to go with a bedroom and a supplementary roomette for Grandpa, since I think the family bedroom probably won't work by next summer, since she is already nearly five feet tall. I need to book in the next couple of days, I think. What are the can't-miss-with-kids things to do in our stops? Many years ago, we did travel with her mom as a kid, but our granddaughter has a rather different personality--brash and active, rather than quiet and day-dreamy. Am I crazy to try to do this?
n the San Diego line. Part of The line is closed because of land slides.
As far as what to do in which cities, I'm afraid I'm not much help there, as the only city I have even the smallest amount of knowledge is Seattle, which you don't need any advice about.
I would encourage your granddaughter research what there is to do based on her interests. 
