I've always called it DC National/Washington National. I know a few people who call it Reagan, but that's hit-or-miss.
In Philly...the issue is that while Market East was a slapped-on name, Suburban Station has been Suburban Station for a long time. Also, while Penn Station might be obsolete, I know a lot of folks in Baltimore wll refer to it as Balto-Penn (to distinguish it from NYP...or the scads of other "Penn Stations" in the past). I think Amtrak actually tried to force the city to start calling it "Baltimore Amtrak Station" or somesuch...and that went over about as well as the statue in front of the station did.
In Philly...the issue is that while Market East was a slapped-on name, Suburban Station has been Suburban Station for a long time. Also, while Penn Station might be obsolete, I know a lot of folks in Baltimore wll refer to it as Balto-Penn (to distinguish it from NYP...or the scads of other "Penn Stations" in the past). I think Amtrak actually tried to force the city to start calling it "Baltimore Amtrak Station" or somesuch...and that went over about as well as the statue in front of the station did.