Also count me as another vote against a giant post office. I was picturing something small enough to maybe even fit on one floor of the old White House. I can't imagine each user having a whole chest for every other user. That's just silly.
Not all projects should have to be huge in scale. Bigger is not always better. I think some of the small scale projects actually turn out the best. I loved Bonn's old BP house for example even though it may have been "small" by some standards. Same goes for my old White House.