Well, I had written a pretty lengthy trip report (with pictures and videos), but my stupid fingers decided to hit the back button 3/4 of the way through and I lost everything. I'll get around to it eventually, but I thoroughly enjoyed the trip.
Got to touch snow for the first time. The scenery in Virginia north is beautiful. I do plan on taking the train north to Philly again, but spending the night so I do have time to see the sights.
I did see ACS 600 and 601 in DC. I also spotted another one at the Wilmington shops coming back south. Not sure if it was 600, 601, or a new one.