My other reason for picking DC, is that it'll hopefully give me a chance to snap some pics of #1001, Beach Grove (one of my fav cars)
Be careful doing that, as they seem to have gotten a bit paranoid down there in DC of late. NY is the prime target, but DC has gone nuts on security.
I'll second that. If seeing the Beech Grove is 50% of your reasoning, throw that out of the window, because I'd give you a 15% chance of being able to snap a picture of the car, and here's why:
1). The car isn't always parked in-station. In fact, since Gunn and Hughes left (both of whom loved the car), I've noticed that it's not in the station as much as it used to be. If it is, it's always on track 18 (I think I've got that right; regardless, it's closest to the eastern upper-platform station door).
2). As Alan notes, security—especially on the platforms—has been seriously beefed up. They don't just not like you taking pictures—they don't like you dawdling at all. Either you're getting off a train, or you're getting on.
3). Tracks 17 and 18 (again, I'm foggy but I think those are the upper-end numbers for the upper platforms) are now physically quarantined off from the rest of the upper-level tracks with a swinging cast iron gate that is almost always closed. Since the upper platform is routinely patrolled by Amtrak Police, Red Caps, and other station personnel, you'll be noticed if you start wandering over to track 18 to take a look at the BG if it's there.
I hate to be such a drag, but I'd hate for you to get your hopes up and then be let down. Now, there's nothing wrong with just asking someone if it's okay if you snap a picture if you get noticed. You may get lucky and get someone who's willing to walk you over, but odds are they're going to politely say no, unfortunately. The other way to get a picture of the BG if it's in-station is to be boarding or detraining a train that's on the adjacent track. That's almost exclusively going to be an Acela, however, and I don't believe that that would be your connecting train.
Rafi