I bring one tee shirt and one uniform shirt/duty period, one casual shirt for each layover where I'll where it for more than 3 hours (if less, then I can use a shirt for more than one layover sometimes), 1 pair jeans, 1 pair shorts, 1 swim suit, running shorts, running socks, running shoes, spare uniform pants for trips more than 3 days, electric plug adaptors for around the world, shaving kit, med kit (bandaids, OTC meds, antibiotics, etc), pair of casual shoes (don't like to wear uniform shoes and like better looking shoes for uniform), casual jacket if going someplace I'll need it.
All that fits in a regular carry-on size travelpro,for trips over 7 days I bring my purdy neat things bag to fit it all comfortably. I also fit in that one my international jepps, as I keep my laptop in my crew bag, so I end up having 2 binders and 3 chart books in the regular bag, the parts I am not using go there.
So, I carry my scott leather flight case and my purdy neat things bag to cover all of my needs for up to 14 day trips.