I am going to be in town for the December 10th Eclipse over a DC landmark (http://events.starcircleacademy.com/events/42364592/)... so I was looking about for other opportunities.
The Old Post Office Tower is open until 6:00 pm on Sundays (http://www.nps.gov/opot/planyourvisit/hours.htm). Perfect to get the city from on high as it lights up. The tower is the third tallest building in Washington, DC at 315 feet tall.
Must arrive (more than) 15 minutes prior to closing and may not have long. Also, they MAY not allow tripods nor a large number of people. After shooting some night views, we can proceed to the south side (where the only open entrance is on Sunday), cross the street and attempt Urban star trails.
Or the well heeled (and meat hungry) can go to Fogo de Chao (Brazillian Steak house / Churrascuria) for dinner. The Old Post Office Emporium (http://www.oldpostofficedc.com/shop.php) closes when the tower does so come early for dinner.
For images from and of the tower see here: http://www.flickr.com... (http://www.flickr.com/search/?q=old%20post%20office%20tower)
Image from Google Street View (http://maps.google.com/maps?q=12th+Street+and+Pennsylvania+Avenue,+NW,+WaSHINGTON,+DC&ll=38.894022,-77.026756&spn=0.010672,0.016673&oe=utf-8&client=firefox-a&hnear=Pennsylvania+Ave+NW+%26+12th+St+NW,+Washington,+District+of+Columbia,+20004&gl=us&t=h&z=16&vpsrc=0&layer=c&cbll=38.894754,-77.02708&panoid=sdaiXoym3oUr-ezkrc6-9g&cbp=12,228.47,,0,-21.31)