My advice is to mix for the song. Even though the record sounds as if it's all over the map there are things the will tie it together no matter what you do. The lead voice is one. Even singers who change up their tone always sound like themselves. There is also you. Every mixer has a certain aesthetic and reacts to things a certain way. I know I do.
A subtle trick I use is to re-use certain things. Keep you sub-group compressors consistent. Change their setting to work for the song, vary their levels as needed, but keep 'em the same. They have a tone that is imparted on what they are hearing. I sometime re-use effects. On a record I'm mixing right now, I used a long delay on one word. I mixed is very far in the background. On another song I use the same delay on the guitar solo, but loud like a stomp box. I doubt anyone will make the connection, but I believe it subtly ties the songs together.