I have flown several 4 hour flights with my daughter starting at 6 months. I agree with the visual toys and DVD player with headphones or no sound. Also, I tied a long piece of yarn to her toys and held on to the end so that if she did drop them, I could pull it back up off the floor with the yarn.
Also, the bathrooms on the plane do have a changing table that is fastened above the toilet. I never knew that until I asked. The flight attendant was more than helpful to assist me in holding the baby outside the bathroom door as I got set up inside for changing and then afterwards as I cleaned up. I bought disposable chuck-pads, the kind they put under you in hospital beds, at Sam's Club in the maxi pad isle. They are large enough to cover a whole changing station table, and a whole box is $24 or so and lasts me almost a whole year. I lay down a disposable chuck pad on the changing table and then roll up the stinky diaper in it and put both the pad and the diaper in a scented plastic baggy that I buy from Target and Babies R Us.
The only problem I have had traveling is when I have gone through security and been questioned about the amount of breast milk or formula I had in my bag. Just remind them that flights are often delayed or cancelled and the airport does not sell formula. You don't want to run out and have a hungry, screaming child on board.