We split resorts last year for the first time and it went so well that we decided to do it again when we go in 2 weeks. I was apprehensive at first because I do like to unpack and settle in the room, but it went OK. I did try and keep the clothes split between the 2 suitcases as you mentioned, and that seemed to cut down on the unpacking/repacking. I also use the ziplock bags and swear by it. Yes, the clothes look a bit smushed and I too am an anal-wrinkle-obsessed mother, but I was able to live with it, There were a few wrinkles, but not many and once they had them on for a bit I hardly even noticed.
I pack large canvass totes and use these to store bulky items such as water bottles and such and it worked out. They moved all our groceries, many of which were in plastic bags, without any problems. In addition to our park backpack we packed a tote bag with swim wear and such to use while we waited for our luggage.
This year I fear I will be embarassed when they come to pick up our luggage. My sister is joining us with her 3 teenagers when we move over to AKL and as she is getting in late she has asked me to pick stuff for her on our town car grocery stop. As a small family of 4 we will look like hogs hauling all the soda, wine, beer and munchies from one resort to another!