I have two suggestions....let the kids help find something to do and have them show you around, they probably know lots of fund places to go and they'll feel excited to be a guide.
Secondly, use this time of longing and missing to think about a special homewarming when they return. Sure it was only a couple days and they needed the time together but this will welcome them home with love and make the weekend more special.
Redirect the energy. From experience this is the one thign that keeps me sane!!