Of course, by infant I'm really talking about a child under a year old, as anyone knows with toddlers it's a whole other ball game (if you're feeling brave you can read my nightmare story here) and a separate topic entirely.
Here's the thing with infants: they really will be sleeping or feeding for the majority of the flight. I can remember being worried about the pressure on Baby S' little ears, but as long as I was nursing or bottle feeding her going up and down, I didn't notice any issues. Having your diaper bag packed with all the essentials will aid peace of mind, and bringing a Boppy or travel pillow of some sort (if you have the room) will make you and baby more comfortable. As baby becomes more aware of his/her surroundings, bringing a few toys/books/DVD player are a must, and as mentioned in the video, a brand new toy is a good thing to bring out if tears are on the horizon.
We all know flying is a hassle these days (with or without a Little One in tow), but I also believe it is the most convenient way of travel -- at least for my family. Hopping in a car has its advantages, of course, but if your families are scattered throughout the South and Midwest like ours are (and time is usually of the essence), there's really no other way to go.
Good luck, and check out Momversation for more videos from moms with an opinion on all manner of subjects!