"Must have" Family gear:
Tent
Sleeping bags & pillows
Cots for adults, pads or cots for kids
A couple of changes of clothes
Personal toiletries (toothbrush, deoderant, etc)
Flashlights
Extra money (for the inevitable Wal-Mart run on
Saturday afternoon).

Leave at home:
Family pet
Alcohol

"Must have" Shared gear:
Food
Cook stove
Cooking utensils
Propane lantern.

Suggested additions:
Sunscreen
Mosquito repellant
Bicycle for kids
Cards, board games, dominos, etc.
Fold-up camp chairs
EZ-Up canopy