We've stayed at CSR several times, last time was fall 2018. The Tower wasn't open yet and construction was awful! And housekeeping was horrible... but that's another story!
Regarding buses..... in my opinion, you are better off with standard room either at Casitas or Ranchos. The first stop (pick up and drop off) is stop 2 right by Casitas 4. And now with the bridges, it should be a quick walk to the main buildings.
Then it loops to stop 3 over by Ranchos 7a, then to the stop by Cabanas, and last.... the stop by the main building that everyone from the Tower will use.
Honestly.... I think it's a bad situation for the guests staying in the Tower because the buses are often full by time they make it around to that last stop.
So.... If I were you.... I would request something in Casitas 4 or 5, or Ranchos if you want to get a seat on the bus! We love both sections of CSR, with Cabanas our least favorite.