I fly long distance flights frequently. Usually 4+ roundtrip transpacific flights per year, with additional legs once I get to Asia. We're talking 14+ hours each route, so 3+ hours would be considered a short flight for me. Even LAX to JFK takes longer than 3 hours.
I'm usually asleep before the flight takes off. If I'm really tired, I usually sleep through the entire flight, but awake in time for the breakfast meal (2nd meal). But I'm usually awake only for the 2 meals I'm served, and rest of the time I'm sleeping.
Invest in a good noise-canceling headphone like Sennheiser PXC250. I never travel without it, and I always make sure the batteries are fully charged before each trip. I put the headphone on, turn on the power, turn on my Ipod Nano, and that's what helps me to sleep through the entire flight.
I will only fly Cathay Pacific or EVA (upgrade to Business using my FF), and both airlines have good personal TVs with good selection of movies. But I only watch those while I'm eating my meals.
Flight attendants in both Cathay and EVA are gorgeous!