i flew nonstop from chicago to honolulu a few years back. my advice: book your flight to hawaii to leave around 5 or 6AM. that way, you can catch up on your sleep on the plane and be refreshed when you land.
yes, they showed 2 movies. i had a book and a drink or 2. i talked to my friend. i wrote in my travel journal. i even drew a picture of the entire rest of the plane as seen from my seat. (yes, i was THAT bored!)
get up to walk as much as you can. drink LOTS of water!!!!! you'll be amazed at how dehydrated a flight that long can make you. if the airport security allows it, take some lotion on the plane as well.
in all honesty, i'd never do another 8 1/2 hour flight if there was an option for a layover. even an hour or 2 would have made a huge difference!