We just did a trip with my inlaws, but thankfully we paid our way and they paid theirs, so we spent less time worrying about what the other was doing. We rope dropped almost every day- otherwise we had 9/930am ADRs. Nana is not an early riser- and she spends hours getting ready in the morning. Rope drop was out of the question for them. We traveled together to a breakfast ADR and were almost late- had we met at the bus stop at the time I suggested, we would have been able to take a leisurely monorail ride to CR just for the fun of it, but instead we took the faster, walking path (which Nana complained about the entire time) because I was not going to run the risk of being 1/2 hour (or more) late to our ADR and possibly lose it/be charged a no-show fee. On days with lunch ADRs, lunch was the first time we saw them for the day. There was one day where they didn't show up to a dinner ADR (Nana had even tried to cancel the reservation, since we were linked as 'friends and family' in
MDE, but thankfully it wouldn't let her since it was in my name / my credit card). Before booking these ADRs, I made it clear that they didn't have to do them with us, they could do their own dining reservations if they didn't like the restaurants or times we picked, but Nana was insistent that we eat all of our meals together...until we actually got there. I did not book FP+'s for them, but I told them what our FP+ plans were and they booked the same ones....and then they didn't show up to ANY of them. In short, we barely saw them all week because they spent more time in the resort room than in the parks. (This was not their first WDW trip; they had been the previous Christmas with another set of grandkids, they knew how ADRs and FP+'s worked, and they had stayed offsite then. If they had slept in so late while staying offsite, I don't understand how they saw anything in Disney at all- they didn't stay out late enough for fireworks, either.)
Our little family (hubby and I and the kids) had a great time and did everything we wanted and have made memories that will last a lifetime- but for the most part, these memories do not include the grandparents. The whole reason they came on this trip was to be with their grandkids, but they just didn't want to do any of the things we wanted to do. I'm not sure why they spent all that money to hardly do anything at all; they bought the dining plan and I'm pretty sure left with unused credits because they kept skipping ADRs. I assume they had a good time, and I know we had a good time, but it wasn't a trip that we went on "together". It was more like we occasionally ran into them a few times while we were there. I made a calendar for them for Christmas with our vacation photos and I really struggled to find photos that had them in it- we had lots of meet-and-greet FP+'s that they neglected to show up to, which would have been wonderful photos for such a thing. If I had paid their way with the intention being a trip where we all spent time together then yes, I would have insisted that they tour the way we did so that we actually spent time together. (I would have been severely insulted if they had wasted dining credits I had paid for- that's literally throwing away money.) Similarly, if they had paid for us, I would have been more intentional about sticking to their schedule- which would have meant laying around the resort doing a whole lot of nothing, and I would have been disappointed that my kids' first Disney trip wouldn't have involved much Disney at all.
The lesson I've learned is that we're pretty much never doing Disney with extended family- unless everyone involved is okay with the "we're at Disney World at the same time, but we're not really there together" strategy, which works best when everyone pays their own way.