OK, look, I've heard people suggest Benadryl before, and, aside from my own feelings about drugging children unnecessarily, PLEASE DO NOT do this unless you know your own child's reaction!!! My DS has the OPPOSITE reaction to Benadryl, and many, many other children do, too. We once flew with him when he was sick and was on Benadryl as prescribed. He was absolutely bouncing of the walls because of it for 2 hours on our flight!!

It was the worst trip EVER! I know the PP may have been mentioning that tongue-in-cheek, but I always have to share my experience with Benadryl.
That being said, we've flown many times with lap babies, usually without problems. We always bring TONS of snacks (lots of different kinds), books, with DVD player and without one, lots and lots of activities (I read once to have one activity per 30 mins of flight).
I just bought "earplanes" to help with ear pressure during flight, but snacks/drinks (lollipops were our special treat) also work. I bought them this time because my DD (21 months now), for some reason, would not eat/drink last flight and was quite bothered.
I never felt that they were unsafe. We've even been through turbulence, but I held on to my babies so tight I could have squished them!
I have to admit that I'm nervous, too, about this flight, only because DD has, in the past 2 weeks, become a squirmer/runner and I don't know how this flight will go. In the past, the hum of the engines almost always put them to sleep for awhile
best of luck!!!

in training