I still work through my kid's summer, so I try to plan certain outings on the weekends. Tidepools, museums, street fairs, picnics at the park, etc. It helps to have things to look forward to during the week while he's in summer camp.

We keep up on reading every day. We have weekly boardgame or card game nights.

Honestly it doesn't change much from when he's in school. I try to keep it consistent, including bed times, so that the transition into school isn't more difficult.