Maybe just start them off all in a crowd of people watching a bard playing a song or something and the crowd is attacked by evil city guards that ban music playing in the city. You and the group fights back and escapes: the typical Robin Hood & gang scenario (outlaw bunch).
Or how about a council meeting... all characters represent some political force.
Or what about an 'invitation-only' party to some exotic tower out in the middle of a dead forest. The typical Dracula start... ;)