For Tsunade, let's not also forget that it was because of her that most of the shinobi survived Pein's attack due to her basically casting her healing onto as many people as she could through Katsuyu which resulted in her ending up in a coma and almost dying, with no knowledge of whether she'd awaken or not.
I would have preferred if Danzo had turned out to be "Madara"/"Tobi". That was an actual (unintentional?) red herring with the way you always saw Danzo's right eye covered in bandages, yet "Tobi"/"Madara" always had his right Sharingan eye uncovered, but his left eye covered with the mask. Not to mention their hairstyles looked a bit similar, Danzo's manipulation to become Hokage, finding out his collaboration with Orochimaru to allow him to invade Konoha during the Chunin Exams, not assisting in the defense of Konoha when Pein attacked, and so on; all in some grand conspiracy to put Konoha in charge of the world with himself at the head.