C&O canal to Pittsburgh via cumberland MD.

[BrianW]

Yes, parking at Great Falls and biking into the city allows you to truthfully claim that you've ridden the entire path! :-) The section just after Great Falls, going toward D.C., is really pretty, running along a small man-made lake. It's all path until you get to Georgetown, where you'll then be back in "civilization."

I've never had an issue getting bike boxes at AMTRAK's Philadelphia station. Not sure if you can call ahead to reserve. I think they are around $10-15/box. I usually buy two because I'm generally shipping a tandem, and they have always had enough. The baggage people in Philly are always remarkably friendly, too. I've shipped three tandems cross-country on AMTRAK with no problems at all.

Personally, I'd still seriously consider the rent-a-car and drive yourself option. A lot more flexible, and probably not that much more money. A quick Travelocity search shows around $240 for a one-way rental in late May. Just get a minivan/van and you should be fine with four people and bikes. Split four ways that's reasonable, even with gas and tolls.

[BB]

There's only two of us and we'll need our own car to get down there, as mentioned above we are making other stops on our way 'south' from Maine (like way out on Long Island).  So we'd still have to leave our own car somewhere.  But it's worth thinking about.  We like train travel though too.  It is too bad the arrival is so late into PIT. 

[BrianW]

RE: rental car. I meant, leave your own car in D.C. (like at Regan National airport, which isn't too hard to get to on bike) and rent a car one-way from there to Pittsburgh. Even cheaper, then, if there are only two of you, as you don't need a minivan. Just make sure you get a rental car where the rear seat folds down (most sedans do this now).