What exactly is this "US trip"? Lots of car time? If your kiddos could handle lots of time in car, I wouldn't skip Yellowstone. There are lots of great views that require a walk, not exactly a hike. I'm not really into hiking either. I'd skip Grand Teton.
(As part of a two week trip, we went to Glacier and Yellowstone/Grand Teton. Did the seven hour guided hike to Iceberg Lake in Glacier NP. It was beautiful, but arrived back at the car in such pain (leg and knee), I would not have been able to drive. I was doing nothing even remotely like that the following week in Yellowstone. We did mostly walks of about 20-30 minutes IIRC, and had a great time. I was underwhelmed with Grand Teton. This was pre-kids.)
Basically for the last four years the DW and i have been trying to visit all states, mainly leveraging our SW CP.
Now that we have two children and two Companion Passes we are hoping to for our fourth time with all four of us.
Reading the few posts after your reply is why we have stayed away from the national parks until now, we are lazyish and enjoy staying in a nice hotel and maybe doing one or two big things in each state (we have roughly two months).
Problem is, we did already most states and only have some states with big parks left.. This summer I hoping to do Minnesota, both Dakotas, Montana, Idaho, Washington and Oregon.
Just a bit confused about these huge parks, if its worth it driving around to some of the famous places within, taking some pictures and leaving.
Having a stroller or two wont make hiking to practical and - like i mentioned - its not our thing.