Depending on your finances, day trips are nice. One day at a children's museum, one day at the beach, miniature golfing, local activities [band concerts] craft fairs,or have your own craft day at home. Hiking and a picnic,swimming at the local pool,yard games,and a special favorite of mine is having a card activity where all of you make greeting cards to bring to the local hospital [children's ward] or senior center.
Some towns offer boat rides around the local lake/pond. Plant a garden and watch how your garden grows. Plan a journal of your summer activities . Makes a good topic when the kids are back to school and need to write about something special that happen to them. Read the local news about what is going on in your town etc.. Have a great summer!.