Every time our family has an early flight, we cut it close. The shuttle or taxi usually arrives just as I'm about to lose my mind. Then we head to the airport and have to kill time with irritated kids. Getting two tired tots up, bathed, and dressed can cause parents quite a bit of stress. I've noticed things run much smoother when I treat my tots to a bubble bath the night before and let them dress for the next day before hopping in bed.
They think it's wild to wear clothes as pajamas and my husband and I don't have to worry about the extra time it takes to get them ready. Since we can carry them straight from their beds to our transportation, they are also likely to sleep all the way to the airport. This tip also works for wee-hour-of-the-morning road trips.