Getting cookies to survive the trip to your Cookie Monster in the sandbox can be a bit of a challenge.

Choosing the right kind to send is the first step.  Remember, CHOCOLATE MELTS at 140 degrees.  (Actually, it melts at about 95 degrees).  So, especially for summer treats, try to limit the amount of chocolate for best results (minimal amounts should be ok).  Bar cookies are sometimes easier to pack.  Recipes with white sugar and vegetable shortening are best bets to avoid spoiling in general.

Packaging is very important.  The best method, through trial and error by many spouses, seems to be to wrap the cookies in small stacks in aluminum foil, then to pack these little stacks into glad ware containers.  Finally, seal the container in a ziploc bag and pack into a box where it is well cushioned and with little room to move.  I have heard that putting a slice of bread in the gladware container might help keep the cookies soft and not mushy, but I have not tried that myself.

Nestle has a page with a few more hints, as well as some recommended recipes.  Above all, remember to pack enough to share.