I'm worn out reading that list! In addition to clothing we include:
small bag w/blunt ended manicure scissors, moleskin, emeryboard for foot care in the parks;
ziplock bag with camera and film;
medical bag with ibuprofen, immodium, sinus meds and motion sickness pills, vitamins (all in film cannisters to minimize space/weight);
ponchos, glo-in-the-dark necklaces for evening parades (check the dollar store), ziplock with hand-towel for drying seats;
spray-on antiperspirant for feet so they don't sweat and blister;
park snacks (we find chewy granola bars and fruit snacks- the gummy ones- work best);
Bathroom Bag: to minimize luggage (both space and weight), get small squeeze bottles from wal-mart (about 50 cents each) for shampoo, conditioner, dish soap, etc. Also bring laundry tablets and dryer sheets if you'll be doing laundry. Buy travel-sized tube of toothpaste, waterbabies sunscreen stick, chapstick with sun protection.
BRING PLENTY OF ZIPLOCK BAGS- keep anything you want to keep dry in your backpack in them. Drinks, snacks, etc. are easier to find in backpacks if they are in see-thru bags.
Check with hotel- many include hairdryers in the baathroom.
Of course, I went on one trip with three days' worth of clothes, toothbrush, hairbrush, makeup, backpack and credit card. I was great, just bought what I needed in FL! Walgreens, Krogers, Albertsons are all cheap, and wal-mart is just a few miles down 192 east of the parks if you forget anything MAJOR!! I'd rather travel light and easy and make do with what I have. Can't stand multiple heavy suitcases!
lane, park 
