Thanks for all the feedback. I doubt my friends will be willing to do so much extra walking. I'll have to explain the situation to them and see if they wouldn't mind going back and forth. Only 1 day in DHS is so tough to plan now.
I'd probably ask my kids what they want to do the most, and split from my friends, if we have different priorities. It's one thing to prioritize something over something else based on my immediate family, when there aren't enough adults to go around, but I'd have a hard time telling my kids "you don't get to do your most important thing because we're here with this other family, and they don't want to walk that much."
To me, part of the benefit of going with another family is that kids can be split based on interests and age sometimes.
Just last week, I was at a children's farmstead with my extended family. My 7 year old son was pretty sulky, so I asked him what was wrong. He said that "Gaga" (my Mom) told him he couldn't do the gem panning, because there were too many people. (an argument I heard a TON as a kid, because my Mom has a very 'more the merrier' personality) Meanwhile, his cousins and sister were pretty much getting to do everything they asked to do. So, I decided to split from the rest of the group and backtrack to take him to pan. It was literally the only thing he was interested in doing while we were there. We live out in the country, so he gets to interact with farm animals on a regular basis.
Yes, you will inevitably skip things, but JTA was a highlight of our last trip, and we only go to Disney once every 2-3 years. If the new rides are awesome, then they'll still be there on our next trip, while my son may age out of JTA in the interim.