Here is my list. I'm sure it's missing something and I would love to see what others have to add, there's always room for improvement! Especially if it makes the trip easier and the kids happier.
Wool, fleece, poly, and/or nylon clothes only. It's important that there is no cotton, even undies and socks. The only exception would be when it's super hot and you want a cotton shirt to keep wet for cooling.
California Baby | Natural & Organic Products | Official Site
(love this stuff, esp the stick)
Natural Insect Repellent - Great against Mosquitoes, Ticks, Gnats, Flies, Ants, Black Flies
or Organic Anti-Bug Balm by Badger - All Natural Insect Repellent
Sting Stop (for the nasty bites you'll always get)
Great Homeopathic remedies - - By Company - Boericke & Tafel - Topicals - Stingstop Insect Gel
first aid (should have age specific things, such as homeopathy for teething or fevers)
beanie or balaclava (cold temp sleeping)
rain coat/pants (ponchos are questionable)
rain boots (no liners for quicker drying)
Kamik - STOMP
Keens (good for off and on river)
fleece lined jacket with outer wind layer
long undie shirt/pants
long sleeve swim shirt
quick dry sun shirt
quick dry sun pants
socks, thin and thick
bag for dirty clothes
Big Agnes Sleeping bag with pad pocket. It helps to keep them warm and on the pad.
children's binoculars, compass, magnifying glass, headlamp
sand toys/water guns
Lots of fruit (grapes are great), yogurt, healthy trail mix, cheese & crackers, energy & protein bars
Keep a small lunch set of utensils handy in the dry box
REI sales are a good place to go, or second hand stores
Patagonia, Solumbra or Coolibar make some nice stuff, but pricy
Sun Precautions,30+ SPF Clothing
or Sun Protection Clothing For Children, Kids Sun Protective Clothing – Coolibar Inc.
Have fun most of all!