If anyone remembers Neverwinter Nights 2 I think had an optional system where you could get EXP from resolutions not just killing. As I remember it it worked quite well. I think being able to use Skills to intimidate or charm an enemy into seeing things your way while avoiding combat makes the game more interesting, though probably harder to program. Maybe not for mooks but I think if you're dealing with a named opponent and there is a possibility of a peaceful or Skill based solution you should get EXP for it. You should probably get more EXP for it because you aren't going to get any of their equipment/valuables etc.
