First and foremost - I am green with envy! Sure wish Alan and I were packing for PIP too! :(
We've used both the ziplock bags and the space bags. I really recommend using one or the other. You'd be amazed at how much you can get into your luggage after squishing all the air out of the bags. It also makes for great organization, rather than the clothes remaining loose in the suitcase. Especially, underwear and socks. Everything is compact. And, this method did cut down on wrinkling.
We also cover suits, dress shirts, skirts, dresses, etc. with long dry cleaner bags before hanging them in the wardrobe suitcase.
YOU GUYS ARE GONNA HAVE SO MUCH FUN!!!
Now, back to sulking for me! :(