The only game I've ever seriously leveled up in was Star Ocean: The Second Story, and it wasn't just for fun. I got to one of the final bosses (two fights before the end) and realized I had to fight two guys who could take me out in about 45 seconds. I had to gain a solid twenty levels, and won by sheer tenacity and luck...and using items like crazy. I've never really enjoyed leveling up--it usually gets boring, and there's no real need. I have a friend who likes to brag about "beating the crap" out of a certain game, be it an RPG or a Fighter. I think it just makes him sound stupid.