1. I wouldn't recommend this show to anyone without young (middle school or younger) girls. Even at that, I would recommend begrudgingly. (My then 7 yo son was extremely bored, by then 10 yo daughter "liked it" at best.)
2. And I agree with the other posters: why would you bring your grandparents to a children's show? (The idea to bring them to theater, though, is a truly lovely one.)
3. And yes, I think South Pacific is the IDEAL suggestion for them. It's a beautiful production (although I've heard the replacements are far weaker than the originals).
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.