"Vivian" is neither common or rare. The first thing that comes to mind when I think of Vivian is the actress Vivian Leigh, who played Scarlett O'Hara in the movie "Gone with the Wind (1939). The second is another actress, Vivian Blaine, who played Adelaide in the Broadway musical "Guys & Dolls" (1950). It also makes me think of the words "vivid" and "vivacious."
"Chloe" used to be a rather old-fashioned name, but it is experiencing a big wave of popularity.