Phoenix is growing in popularity for both genders-- a little
Phoenix will not seem so strange in a few years. Nor will an
Adelaide.
Betty Jean is very familiar, and I highly doubt a child with such a name will be frowned upon, or that people will whisper "Oh, her name is so strange!" to each other. Plus,
Betty's got a similar sound to Maddy, which is epically popular.
I'd worry more about prn issues, or really horribly dated names.
Caoimhe and
Doris will have much more trouble than
Betty.