A couple of disposable 'ice packs' from the local drugstore chain would be nice also. They'll assist in anything from a bee sting, a sprain, a burn, a broken arm or sunburn. Should you be renting a vehicle at your destination familiarize yourself with the vehicle's safety equipment, including hazard lights, windshield wipers, the spare tire, seat belts and door locks. Make sure you have enough gasoline. The Pets really don't want to see the Liberty Bell, Smithsonian or a water slide.
Many attractions bar their presence.
Do them and yourself a favor, and make arrangements at a reputable kennel for the time you're away. Ask your Vet for recommendations. It is cruel and oftentimes deadly to subject a pet to this. Many stores carry magnetic board games such as checkers that are just right for travel. Be aware of the children's activities and locations at all times.