A five hour flight isn't really much. I agree - bring reading material. As an East Coast girl, I say plane rides are like beach trips - bring Cosmo or a romance novel. Save the Neitzche for Harvard Square to fit in
You'll be bringing your toiletries with you on your trip - just stash them in your carry-on and you'll be able to brush your teeth and wash your face in the airport bathroom when you arive.You really don't need anything that isn't already in your purse (i.e. lip balm).
I bring a facial spray (The Body Shop makes some good ones) to keep me skin fresh in the uber-dry plane air. Bring some gum to keep your ears from popping and you're all set. Honestly, as a veteran of 80+ legs and many 14 hour flights, you're really overthinking this
I'd be more worried about transitioning from car-culture to walking culture - making sure you have comfy shoes and a good coat.
Now lets get to the really important stuff - what are you wearing that weekend??