I know this will not be a popular opinion, but I would suggust you get a seat for your child. Ds is a frequent flyer and I would not recommend lap baby. First and foremost for safety reasons (turbulence can be pretty strong and in case of emergency procedures require lap babies to be placed UNDER the SEAT -(google sioux city crash) there is legislation to no longer allow lap babies due to safety. Second - ds is so much happier in his seat. We just flew 1.5 hours each way and ds was the only child in a car seat (ds is 5) and I was amazed at how many frazzled parents were struggling with screaming babies. I almost offered his seat to a mom struggling with a baby who was obviously overtired and couldn't settle. Ds is comfortable in his seat, he can see better, his legs fit better then in the airplane seat, he is secure, and it is part of his travel routine. Oh yeah - his legs don't end up kicking the person in front of him either (like they would he if just had a belt).
By the way I am a single, disabled mom and I still manage to lug the carseat, stroller, and carry on; although watching me check the luggage for our two week trip wasn't pretty, lol.
I do second a dvd player, snacks, small new toys, magna doodle, although ds has only needed his headphones (to drown out the screaming babies) and the mags on the airplane for the last few years.