I mostly fly internationally, and have to have a checked bag; this is rather heavier than it would be if I were going carryon-only:

Backpack
Laptop Pocket:
Laptop
Couple of magazines
Hotel/Flight confirmation printouts

Main Pocket
clean shirt, clean underwear (sometimes 2x), clean socks (folded at bottom for extra paddding, either as spares or to change into at lounge)
Notebook (paper) or graph pad
Old AA amenity kit (see below)
Baseball cap (if going someplace sunny)
Umbrella (if seems likely needed for weather)
Spare eyeglasses
Camera
(sometimes) spare laptop battery
(sometimes) bulkier food items or snacks
Maybe a book or two
Often my jacket stuffed in the top
Once through security, often a bottle of water stuffed in the top

Outer side pickets
Medication (one side)
Laptop power cord (other side)

larger back outer pocket
8" tablet
Spare eyeshade
Freedom baggie
Smaller snacks
house keys (clipped to interior zipper)
USB AC charger

outermost back small pocket
Sunglasses
A pen
bar of soap
Airline DC laptop charger (if flying an airline that still uses it)

Old AA amenity kit case containing:
* assorted cables (in ziplock)
* assorted memory cards and USB drives (in another ziplock)
* spare earbuds (in another ziplock)
* pens and pencils
* mini-screwdriver
* backup travel cell phone

Vest zipper pockets
Headphones
Cell phone
passport
wallet
Boarding passes
Eyeshade
Retractable micro USB cable
lens cleaning cloth


pants pockets
Usually end up with some napkins or tissues
...and maybe small denomination loose currency