C) Go to the airport 2 or 3 hours before the scheduled departure. Unlike the telephone staff, the airport staff have a range of options that they can try out, though I can easily imagine that on a Friday it could be tricky finding a suitable alternative (though EWR, BWI or PHL are obvious ones due to the fast train service from those airports to Washington).

From an irrop point of view, it's quite important to understand the difference between telephone and airport agents, also the distinction that applies when a service is under "airport control", and what services are under the Joint Business Agreement. Telephone agents are restricted to rerouting on JBA flights. Before ringing up you may want to reflect on that, just in case some note goes on your PNR stating what options you have been given. Also you only get one involuntary rerouting easily, so if something better crops up then you can't expect to have access to it unless there is some other significant factor.