Oh, I definitely have a legendary dinning hall for happy thoughts, I just don't designate it as a "meeting hall", to avoid parties.
I also don't allow my soldiers to carry food, so they get happy thoughts from the waterfall leading into the legendary dinning hall and so forth.
It's just the sculpture gardens that scare me, but I've honestly never experimented with using them to see if the happy thoughts outweigh the friendships made.
I do have one large family that I try and keep safe, although it just occurred to me, that perhaps designating a sculpture garden to this family might keep the kids out of trouble.
Do people throwing parties only invite the dwarves they know? Or would that put my military in danger of making friends?
This barracks will work like the one on the surface in that any uglies that decide to come and play first stumble upon dwarves pumped up by a recent sparring session and ready for action. This method helps advance soldiers combat skills very fast because nothing gives combat expierience like actual combat.
Until I get patrols set up, I do that as well, putting barracks for training in choke points, so any hostiles are greeted by dwarves looking up from sparring with big grins on their faces, ready to test their mettle and their metal.
I agree with doing as much real combat as possible for experience, sending a squad out as hunting party on occasion. I don't use hunters, so the military can do the hunting, gaining skill while providing meat to the fortress well.