Good topic. My typical packing for a 4 day trip looks like this:
2 uniform shirts (1 is a backup, I'll typically wear 1 uniform shirt for a 4 day trip (sorry
@SlumTodd_Millionaire))
4 white undershirts (1 per day I actually fly)
2 uniform pants (1 is a backup)
5 pairs of boxers (I always do number of days for the trip plus one cause you never know...)
5 pairs of socks (nothing worse than dirty socks)
1 pair of tennis shoes
1 pair of work shoes
1 pair of shorts
1 polo (for the commute/deadheads)
2 regular t shirts for the overnights (usually about 1 for every 2-3 days on the road works good since they get limited wear, and you don't always go out everyday/night)
Climate Dependant:
1 company issued heavy jacket
1 lightweight personal jacket for the commute/overnights
1 pair of jeans
1 beanie & pair of gloves
I've got it down to a science because anything extra is added weight, and/or makes my bag more difficult to pack. These efficiencies come in handy as I pack for longer trips. The most I've done is a 10 day trip doing no laundry with the above method, but I only operated 7 legs on that trip.