1) If it is to attract the attention of the politicians then maybe have a million people show up in Washington, D.C. is the correct move.
2) If the motive to attract the attention of the press, then they should march in New York City right on the doorsteps of the major networks. ( This also may be a better way to get the politicians to notice as well)
What's the goal here? To have a good time? To meet old friends and have a party? Or...Is it to work hard and SMART?
Please remember that when the Iron Curtain fell the first sites secured were the TV and radio stations. These freedom fighters understood that their first and most important mission was to get the news out to the people.
Another important goal of the March, is just to be reinforced in your pro-life beliefs. It's all too easy to become flaccid about your support for the pro-life position if everyone around you is pro-abortion. Being with so many others who share your beliefs gives you strength to work for Life when you return home.
50 million pro-life marchers would still not get media attention. A handful of gay marriage marchers, however, would make front page.