Facebook: Ron Paul March
Groups would be great. I'm gonna be carpooling with a few friends of mine, and I doubt we're gonna arrange lodging if we can (just drive there and stop at a motel out of the city if we need to), but I know for others, especially those who live further away, bus or maybe plane tickets and a hotel are a must. The biggest thing is, if you wanna go, just start saving a little now and keep track of when it is (no date has been made official yet).
This idea already has a strong following and preparation is underway. AFAIK the soonest they will be able to get march or gathering permits won't be for a few months, probably June or July. It will be on a Saturday and won't be on any national holidays (D.C. hosts a lot of events on such holidays, you can imagine).