You'll be fine on the Mall and touring the museums. We've had a change of violent crimes over the past few years. There are an equal amount of robberies and carjackings occurring in the affluent neighborhoods as there are east of the Anacostia. Basic stuff. Don't leave valuables or anything visible in your car. Don't sit in your car, stand near your car if you're not actively driving. Do not put your gun under the mattress at the hotel. Maids in DC are trained and will look for guns in hotel rooms.