Travel Insurance
A white board for the kids to leave messages in cabin (DS when he was 12 and above to let us know where he planned to be etc) did not trust the message system on hub or text to always go through.
Ext cord if they have alot of electronics to charge or you want to plug additional items in
Small fan to move air through cabin at night (especially if all of you are in same room)
All the boys can shower and use the bathrooms in the gym (easier for the boys)
Sunblock
Your own straws
Bonine