I think you have made a very wise decision for your family. I also have major concerns about the bus looping and wait times. People used to complain about them at OKW back in the day, but we never had major problems. A few hiccups but it was okay. We were not rope droppers. So I have experience with loop resorts with busses.
What does concern me is the busses not picking up frequently enough from the parks themselves. We all want to be “home” quick. For sure. And I personally, am so jazzed about this resort (my kids are 17 now) I will be pissed if I have to spend hours on my vacay waiting on busses. Or standing on every single ride
Our reservation isn’t until the week before Christmas. I’ve got two options and will land on one within the next 30 days. I’ll be stalking boards to see if it gets better.
I so get what you are saying about theming, etc. it’s why I really think you made the right choice for your family. My scenario on theming is important as well but quite different.
We have been to Barcelona several times. The Barcelona lounge is modeled from the Gaudi house there. Gaudi influence is all over that tower and we love it. It’s everywhere. I see it in every turn. Even the food choices. It is spot on. Even benches outside with mosaic tile, blah blah blah. Because of our trips there, and we love that city, I’m so impressed and passionate about this resort. It’s like Barcelona in a can.
And because of this hotel, I researched the movie Destino. I loved it. While watching it, I was even unsure I was “getting it” but at the end I was crying so I guess I got it.

. Then I watched the documentary about how it got made. Amazing information in that documentary. Walt and Dali being friends. Etc. kudos to Roy Disney for bringing that to fruition. Otherwise totally lost.
Gran Destino is going nowhere. Visit resorts appropriate to what you as a family are doing. Go there when the kid(s) are older and will appreciate it. Your son is younger. He (they in the future) will find magic and delight/life long memories in whatever you pick.
I promise.