I use the zip lock baggies also - do you know you can get TWO (2) Gallon size also? One would probably compress at least a couple days worth of stuff. For the return trip home, you can always use one for any damp bathing suits you may be traveling with. Plus, if you really have to, you could check one of your carry on bags to transport home any liquid refreshment you purchase before going to the airport. I always travel with a little nylon sack that I can clip onto the outside of my bag but unfolds to a good size perfect for the overflow.

You can do it!!!

Isn't it funny how this particular topic is guaranteed to generate a plethora of responses no matter how many times the question is posed?