We flew with our girls Christmas of 2007. They were 2 and 4 months at the time. The difference from your situation is that because Mary Joyce was already 2, we had to buy her a ticket. However, she is very active, and we were somewhat worried about that. We took a bag for her that had things like a coloring book and crayons, small toys, books, snacks, etc. Honestly, she was so fascinated with being on the plane that things went much more smoothly than we ever expected. Big advice--take a stroller for the airports and check it when you board the plane. They will have it waiting for you when you deplane. We got a little umbrella stroller to use since it was less bulky than our regular one, and it was a lifesaver. We had the baby in a snugli, but the 2 year old rode in the stroller. That was so much better than having her try to walk or having us carry her through the airport.