K.R.
Summer bucket list. It might be fun to get two bulletin boards and fun post cards that you are the girls can decorate and write different activities on the cards. One board will have bigger activities the other will have smaller activities. Then have the regular schedule like people are saying with the regular, wake up, do this, do that, okay outside activity.... but maybe each day you pick out something from one bulletin board (think a new puzzle, play a new game, make up a new game, dress up, build a fort, water balloon fight) and then on the day you dont pick from that board you pick from the big activity board (aquarium, zoo, picnic in the park, etc).
Maybe by making the cards with the girls you will also get ideas that they think are fun that you might not have thought of and they will also be more apt at behaving when you go out for bigger activities because they picked that and they feel like doing that activity that day. opposed to 'hey girls get dressed, we're going (here)' 'noooooo I DONT WANT TO GO THEEERREEE"
Good luck!