True, they all need to be happy, but I remember from years ago that they agreed that all three get I think two songs per tour that they can pick that the other cannot reject, so assuming they still do that, that could be one of Geddy's "cannot reject" songs, so to speak. Not that any of them are gonna force the others to play a song that they dislike, but they all still get along so well, my guess is none of them mind making concessions and playing a song or two they may not like that much, if one of the others really likes it and wants to play it.
I find the rumored set list I originally posted interesting in the respect of the CP songs, as "Stick It Out" is a song that Peart apparently doesn't like, but he loves "Cold Fire" a lot more than the others apparently do, so those two rotating would make sense. Given the seven MP songs, the songs they have to play, the new songs, and some of the other mainstays, they might not be able to afford all three getting their two "cannot reject" songs per night, so rotating them might be something they might do.