Well, I'm not HydroGuy, but I thought I'd offer some of my insight FWIW.
I think it will be difficult for anyone to offer a "plan of attack" as you asked for until it is seen exactly how Disney sets up the queues for these new attractions and how the flow of them goes. How quickly they load. How often they dispatch. FP or not. And many other elements. These are all factors that affect how to approach any attraction.
If you "walk with purpose" to TSMM right now, unless you are first, you still have a wait. With Ariel's, logic states that will get divided in half. I would suspect most will head to Ariel's first, but that's a crystal ball situation that no one knows for sure.
When Finding Nemo first opened, the lines were EXTREMELY long for a very very long time. Nemo is a slow moving line however. It does not dispatch a new vehicle every 8 seconds, but rather a large number of people every several minutes. These are factors that affect the queue. There is no FP and it is a long ride, physically, in terms of time once you board.
It's not going to create a new Disneyland. It's two new attractions... with one at DCA at that. Now, when CarsLand opens, that could be an entire new deal!
Once the new attractions open, many of us can offer experience and observations that will hopefully help including them in a touring plan, but atm, it's purely a guessing game.
I'm not HydroGuy, but there's my 2 cents,
Dreams