I would raise my kids vegetarian, there is the inevitable friends houses and unavoidable school barbecues, but, i've allready had my school have vegetarian options at their babecue, they even cooked it at a separate barbecue (no meat juices) Veggie burgers, onion, potatoes, veggie sausages and hotdogs.
If i sent them to a friends house, I'd send them with something to eat

My kiddys aren't gonna contribute to murder!
If they decided when they were old enough to that they were going to eat meat, I'd be dissapointed in them and tell them that if they're going to eat meat, it won't be in my house.
Thats all if i actually have kids.... I'm more inclined to be interested in women atm.... lol.