Before I actually began to write fiction, I was convinced I would write in the first person (if I ever got around to it). Third-person writing seemed odd and distant, a foreign thing. We're used to writing in the first person; it's what we do. We leave notes on refrigerators that say, "I went to the store."
So at first glance that third-person stuff seemed weird to me. I was convinced I could never write that way. It seemed contrived, at least from a distance. So when I decided to write a novel I planned to use a first-person narrator. It sounded easier, I guess.
But when I began to write I found myself telling the story in the third-person. It just seemed appropriate and natural. I was surprised at how readily I slipped into third-person mode -- there didn't seem to be a trick to it at all.
Have you tried writing in both voices, first and third? What was your experience? Did one or the other seem more comfortable? I'd be interested to hear about it.