I guess I have been very lucky. I have played with the same group of people for 15 yrs. and we have never had a serious disagreement. However, we are NOT a band. We are a non profit club, and none of us want to be professionals.
The core group is about 6 of us, others come and go as suits them. We are quite laid back about what tunes we play, and what order we play them in--not set lists, just a play list. Some people want more structure than we have and they just drift off after a while. Who ever starts the song gets the lead, if he/she wants it. We try to rotate around the group so that everybody has a chance to choose a tune.
Since we are non profit, we work for peanuts--sometimes literally. All schools, hospitals, care homes, town-fests etc. are played free. If the producers are making $ or if it is a private party, we get paid the grand sum of $45.00/hr. This goes in a kitty, and we have a blow out Xmas party, and donate the rest to something like the library to buy music with, or the local Arts Council to sponsor a concert.
The biggest problem we have is that since we are a club, we can't/won't kick anybody out, so we get the rude players that walk on people, the guys who only play in D and play there regardless of where everyone else is playing, etc. Most of these don't last long, because we ignore them, and if a gig is really important, we are just selective about who we inform! Cheating I know, but it works!