We just did the trip last week with a 1.5 yr. old, Go to Costco and get the 7in DVD Player for $199 it will last the whole 5 hrs on a good charge, Sit at the back of the plane it's easier to get up and walk around in the back galley.
Also depending on the plane get the 3 middle sits and that will give you all more room.
Our son had tubes in his ears so we didn't have to worry about the pressure change.
Test out before what works better med wise our son gets hyped up on Benedryl ( Damn kid)
Good Luck