I always found lots of snacks, bottles and sticker books helped. Avoid toys that fall on the ground a lot because it is a pain to pick up toys constantly or if things get wedged in the seats (there are/were a number of travel play mats I could buy for my girl when she was that age). If she is off the bottle/breast, just make sure you have a covered spill proof cup and a few changes of clothes - last thing you want is a soggy, unhappy baby.

You will be fine but you might be setting yourself up for future headaches when you fly coach and the little one gets mad that they are not up front. Have a great time.