Yep, haven't done one since...04. I got a little bored with endurance sport, but the feeling of completing a good endurance event is something everyone should do at least once. Be it, triathlon, 100 mile bike ride (heres looking at you Tom), or marathon. Maybe not a lifestyle, but certainly worth doing once.
You'll lose a bunch of your muscle, training for it, because its a different type of fitness.
I suggest doing a sprint or Olympic distance one first. The Half Iron-Man is really grueling. And you can't compete in an Iron Man until you post a respectable Half time (they don't want people dying).
Sprint = 400m swim, 10k bike, 5k run Olympic = 1.5k swim, 40k bike, 10k run
Its quite the experience. Don't spend too much on your bike, and make sure you can swim pretty good!
how did i get singled out for a 100 mile bike ride. =D
Here in MI, they do a 24 hour bike challenge. It might be something cool to try. There are people from all over the country that compete in it. Mind you I am not one of those, I am too much of a fatass, and I look bad in spandex.