I can't say enough good things about the packit cubes and folders. I bought a starter kit a few years ago (1 small folder, 1 medium folder, 1 cube, 1 waterproof pouch). I fell in love with them, and have since picked up a few more small folders and smaller pouches. They really do keep everything neat and organized in your bags. I iron everything before I leave, and with the folders everything arrives perfectly neat.
On my Florida trips I only really use the small folders (I think they are the 15" folders). I use one for t-shirts and one for shorts. I get a bit over organized and go as far as to plan out my clothing by day and stack them in the folders accordingly. Then all I need to do is take a shirt off one folder, and my shorts off the other and I'm all set.
I've even used them in a soft duffle bag, and had everything arrive perfectly.
I had to go last year and buy some new ones, as I let my mom borrow my old ones and she refused to return them.
I bought packing cubes to use for this trip to Disney, one set of small and one set of medium cubes. I haven't figured out how I am using them yet but I think they will help. Probably for undies, bras and socks anything small.