My tips for camping are:
take your normal kitchen knives
dustpan and brush for sweeping out
strong garden rubbish binliners for putting the wet tent in when you take it down (I can never get it back in the bag!)
We have a giant foam groundsheet which goes under the entire tent. Also the sleeping pods are self contained, and there is a seperate groundsheet for the middle section. This means the tent bits stay nice and clean.
We've got an 8 man tent, but you can lift the flaps between the pods, so we use two of the 'bedrooms' for DH and I. Means we can fit in our triple decker air bed.
Take coolbag or box with frozen burgers etc in, and they'll stay frozen for most of a weekend, and keep other stuff cool.
Flash wipes and baby wipes are godsends!
Thick grobags and fleecy sleepsuits for little ones.
Take those cheap plastic storage boxes with holes in sides to use as drying racks. Remember washing up liquid, t-towels and sponge.
We've got a fantastic fold up BBQ from B&Q which goes away to nothing, but will easily hold 6 peoples food.
Try and go away with other people - then you can all take bits of essential equipment. We go with 3 or 4 couples - one takes a cooker, one a BBQ, one all the utensils and pots and pans....
Make a list of what you pack. You can add to it each time, and hopefully forget less and less each time.
Haven't been for a year now, and probably won't make it this year (baby due end of June) so jealous of all you lucky campers! :)