Book a hotel close to the Mall or an easy commute by metro. The Marriott Key Bridge is relatively inexpensive and an easy metro ride from Roslyn to the Smithsonian or Le'Enfant Plaza metro stops. Another good option is the Holiday Inn Washington-Capitol, which is located just behind the Air and Space Museum.
Buy a day pass for the metro and take a metro map with you. The day pass will allow you to get on and off the metro all day as many times as you need. These can be purchased in the metro area where you buy other metro tickets. The metro map is a necessity. There are maps along the stops and on the Mall; but it's helpful to have one handy to memorize while waiting for the event to begin.
Buy shirts that match or some similar technique to keep contact with all the girls. Girl Scout Council sells shirts with the event logo or you could buy several pink shirts. The other option is to dye all the people in your party's hair with Kool-Aid. Don't worry--the Kool-aid will wash out.
Take sunscreen, hats, and water. Make sure you are packed accordingly for the day. There is usually sun in June so be prepared for the hottest of days.
Take food. There are places to eat, but many are expensive and far away from the Sing Along. Take food that won't spoil. Don't bring milk products or meats. It will be difficult to lug around a big cooler all day and you can't just leave them for security reasons.
Pack as light as possible. The girls are not going to want to carry huge bags around the city. There isn't anywhere to leave them, so pack light.
Have a meeting place if someone gets separated. Decide on this and quiz everyone before you ever head out for the day.
Park it. Get your spot right up close and remain there for the day. The experience is much better when you are right in the thick of things. Then sing along!
