Last year when DD 'graduated' from grade school we used it as an excuse to have a backyard campout with her girlfriends. They really seemed to enjoy it and it was not a lot of work. Just a barbecue, set up the tent and play and some games, etc.
Go ahead, accuse me of over celebrating, but I don't care! I know she works very hard during the school year and I have no problem acknowledging it. And goodness (!) we are those same people who are happy to have a family barbecue after dance recitals and go out for a nice dinner after a straight A report card, etc. We are happy to have an excuse to have a gathering, dinner, etc. Oh and to make matters worse, I even give little gifts at the end of the school year, every year. This year we are going for pedicures as an end of year treat.