For travel less than 2 weeks, I opt for my 26L backpack and a personal tote. For travel over 2 weeks/requiring more gear, I'll consider adding my 50L duffel bag. Both bags are water resistant and easy to carry (Kurt is never pleased to see them.) It's also a breeze to pack since I tend to wear neutrals.
I also use a water resistent pouch in case something decides to explode.