The staff at the Hyatt Arlington in Rosslyn are very friendly -- especially if you are a repeat customer. The Hyatt in Crystal City is a "nicer" property, but less personal. The rooms are more bland, although bigger, at the Crystal City Hyatt than the rooms at the Hyatt Arlington. Even my parents (who could care less about most hotels) noted how friendly the hotel staff were at the Hyatt Arlington when they stayed there.