Taryn would be my first choice to go with Danica. They do go together really well but they're each distinctive.
I've always loved the name Callie but it seems kind of nicknamey to me, esp. next to Danica. Maybe you could use it as a nn for Calla, Callan or Calista? It can even be a nn for Carolina.
I like the other names you're considering too but Taryn and Callie are easily my favorites.
Other suggestions:
Brenna
Brianna
Briar
Talia
Caryn
Eliza
GL