I like names that are old fashioned, yet unique to this generation...like Abigail(Abby) and other "old" names.
I think you can do unique names that are mainstream as well. For example, my kids names are Landon and Jade. No really common(although Landon is coming around), but not unheard of either. Do whatever YOU think is right for your family though!
I can assure you that Abigail is not unique to this generation. Dd7 has 3 close friends who are Abigail or Abby. Old names such as Olivia, Ava, Isabella, Sofia and Emily are a dime a dozen.