Of the places described in the article, some are convenient to Crystal City (e.g., Air Force & Iwo Jima Memorials). Also, the Skydome Restaurant (Doubletree Hotel) has a good view and they have 4th of July specials. They're most likely sold out but it wouldn't hurt to check.  

One more thought is that several of the high-rise apt and condo buildings host rooftop parties. Maybe you can advertise a special of your own for a "client with a view."