My suggestions are.........
Batteries
Extra Film/Flash Memory Cards
Power Outlet
Air Freshner
Ear Plugs
House shoes or flip flops (I hate walking on those floors in my clean bare feet)
Itinerary
Card with PS and Reservation Numbers on it
GameBoy for Daughter
Something to read on plane
Dramamine
Just-in-case meds (Allegra, Advil, etc)
Unscented Mosquite Spray
Small First-Aid Kit
Trail Size Toiletries - shampoo, conditioner, toothbrush, toothpaste, lotion, kleenex, mouthwash, shave gel, razor, etc (I throw them away so I have more room in my suitcase on my way home)
Hand Santizer
Ponchos
Snacks for Daughter