Don't forget to check for a bounce back offer.

Make a packing list.

As you get closer to the date of departure, like a week before, set out the suitcases and put things in you will need for your trip but not need until then. Sometimes it's better to go buy things (like toothbrushes, toothpaste, other staple toiletries) and put them all in now rather than everyone trying to remember them the day you're leaving after getting ready.

I always keep my packing list on top of my suitcase, and cross stuff off as I put it in.

I don't know where you're staying when you go (did you say??) When we went to Disney for a week we stayed in a rental home with a washer/dryer so I knew I didn't have to pack something for every single day -- shorts, t-shirts, sock, and undies were washed and worn again. I also didn't pack stuff like shampoo and soap, just ran to a Walgreens and bought it once we were there.

I've gone on some pretty "hefty" vacations with my kids, 7+ days on some of them, and this always helped me get organized.