March 17, 2006 [LINK]
You mentioned that the "main" entrance of the Nationals' new stadium will be in a location where few will enter from, I believe Jacobs' Field is the same way. If I'm not mistaken, most of the available parking is to the north of the stadium, there are only a few small surface lots within a few blocks of the south end of the stadium, as well as the lot where the stadium workers park. I can only recall a couple of instances where I entered Jacobs Field from a gate other than Gate C, where the Bob Feller statue is. Three of the four stadium gates are on the north side anyhow, so it's distinctly possible that they recognized this fact when the place was built.
I know at old Cinergy Field nee Riverfront Stadium, the parking was all in garages and lots which were part of the stadium complex, thusly you parked somewhere underneath the stadium and the gate closest to your seat was printed on the ticket. There's also the unique situation of Dodger Stadium where fans park and enter the stadium on the level where their tickets are, I wonder if this causes a problem for day-of-game sales, if you park and come to find out that the seating level you parked at was sold out.