For me it’s simple: a practical sets version of Soarin, using the same ride system as Jurassic Flyers in Beijing/Arthur at Europa (simulating eagle talons). You would fly over and through all the most iconic locale—Rivendell, Moria, Isengard, Argonath, Minas Tirith, the Black Gate and of course Barad-dur/Mt Doom!
The entrance would of course be Bag End and would transition to the woods where Gandalf leaves Frodo and Sam, where guests would board. However, idk how to hide a show building here, unless Bag End is actually on the second floor. I also don’t know how it could be made ADA friendly.
The unload would have to be a separate environment, likely simulated to be outdoors to make going back into the Shire feel more natural. Throw in Green Dragon restaurant and wa-la!