In addition to everything stated above, I am packing a sponge for washing dishes, a travel size bottle of dish soap, a couple of nightlights, Purex 3-in-1 laundry sheets, ketchup, mayo and mustard packets from fast food places (I hate to waste whole bottles of these things!) I plan to bring a soft sided cooler in case we want to bring sandwiches/bagels into the parks. Once there, I will buy pump hand soap (easier for the kids to use than bar soap).
If you plan to make any recipes that call for certain seasonings, measure them out and put them in a ziplock bag.