These cubes revolutionized the way I travel. If you're on the fence about packing cubes in general, make the plunge and fit, like, 50% more stuff in your bag. Plus, you'll know where all of your stuff is ALWAYS. My friends and fellow travelers are always jealous of my packing cubes and I am always on the lookout for a better one than this eagle creek clean/dirty cube.
The dirty compartment makes this cube my favorite. It's SO convenient to separate wet, smelly, or soiled clothes from the clean ones. The dirty side keeps moisture and smells in very effectively.

This size cube can fit 2 outfits or a pair of shoes comfortably. Or you can pack a week's worth of lingerie or a couple of small towels. Solid choice for a short trip.