At least 2 and if we've done a lot of gigs in a few days then a 3rd one will be the extremely light one to give the back a break(Greco solid body violin bass or a Gibson SG bass or Galveston USA flag bass).
When we do "fun events" such as tailgate parties at Texas A&M(pre-game) then I may bring a rack and 5 or 6 just to compare them all against each other(at volume), because I can, to have spares for young women if we do the "women on stage songs", because no one knows when there time will be up/life is too short not to, give the audience eye-candy, and to tweak the guitar players.
