I wish I liked this place more because it's a great place for a work conference. I lived in the neighboring suburb of Arlington last year and attended a conference there at the time. Although the valet parking in pricey, it's a really nice place for a conference with better than average conference food/snacks. It always annoys me though when they nickel and dime you to print something at the business center.
The rooms are spacious and who doesn't love the "Heavenly Beds" at the Westin. The on-site restaurant/bar "the Trademark" has a good happy hour with a few $5 apps and wines. Other than that, there's nothing worth staying on site for. Any restaurants that are very good are a good half mile or so away on King Street, like Brado, Brado Tasting Room, and Vermillion. Sure, the Metro is a fairly close, but if you're a high heels kinda girl like me, taking a cab is about $18-20 to/from the airport in traffic and a good $30 to go into the city. There are more convenient places to stay in the city and in Virginia unless you need to be in this "Carlyle" neighborhood of Alexandria near the Masonic Temple. Only reason I can think to stay here is if you need to be near the courthouse or the Patent Office nearby.