I fly quite regularly from New Zealand to Canada, which usually includes one 13-15 hour flight depending on the circumstances of the day.

Flying with United SYD-SFO was probably the most painfully boring flight I've ever been on. No IFE and a rude FA (I'd asked for a wine and she said they don't serve people under 21...proved to her I was older than that and then she exclaimed "honey, you don't look older than 16"...she then ignored me the rest of the flight). It was terribly boring....so now I make sure I fly Air Canada since all the Y seats have IFE and a plug for my laptop.

I rarely sleep on planes, so ipod, sudoku and my laptop get me through. I'll Mostly watch tv shows (stop watching for a couple of weeks before my trip and then have a House or CSI marathon) or I'll find a photoshop tutorial and learn how to do something new with my photos. I usually bring a book too, but never get around to actually reading it on the plane...save it for waiting around in airports.