Whether or not they are on bottles, bring bottles to the airport for the actual take off and landing. The new TSA guidelines are tough and my daughter is only on juice boxes as she gave up the bottle so we weren't able to bring the boxes through. We bought milk inside of security, but it didn't help - the staws are too big and uneasy to use. I needed for her to be able to suck down something for the take off for her ears. What a disaster it turned out to be. The next time - almost 3 or not, I am bringing a bottle with me. I don't care what I have to put in it, but at least she can suck on something.
As for entertainment, bring a DVD player - with headphones. We were told this past trip to either use the earphones or turn it off. Luckily, we had 7 of the nine seats, so it wasn't bad.
Sticky decals for the windows make a great time killer if you have the window seat. I let my daughter (out of her seat while smooth riding) put them on the window, peel them off, and start over again.