For me, the attraction of the Great Movie Ride is that it was mildly entertaining, but a long-ish and air conditioned break from being outside. As for Carousel of Progress, I personally find it more entertaining. But I think that one's level of interest in the Carousel of Progress is at least partially tied to their understanding and appreciation for the history and significance of the ride. Not only is it an interesting look at how much technology changed during Walt Disney's life, it was also one of the last major attractions that he worked on. While it could be updated, I don't know that it would be the same without the original scenes. And I am not sure there is any way to add new scenes without removing some of the old ones.
. And it is something we will definitely do! I'm not sure about Toy Story, I thought it had the warning on it for people with heart problems. I'm trying to figure out how to balance what dad needs, and letting the dare devils do ToT and RnR and us lesser dare devils do Star Tours and Toy Story. I don't want dad just hanging out alone most of the time.