I like Dorothy but I love Dottie more. I'd use Theodora or Dorothea with the nn Dottie if I could get an SO to agree to it.
Sally and Dottie is an adorable sibset.
Although, knowing they would give Dottie a full name makes me wish they'd given Sally a full name. And I know, we've had this debate on this board back when they were pregnant, and I actually am now in agreement that Sally can most definitely stand on its own, but Sarah "Sally" and Dorothy "Dottie" = an amazing sibset IMO.