Hi Lydia,
Thanks for your question!
Of the two resorts you mentioned, I would highly recommend
Port Orleans French Quarter for you. It is my favorite moderate resort because it is small, easy to get around and has a quiet, stylized New Orleans feeling. It just feels more adult to me than Caribbean Beach, which is much larger and more sprawling.
Caribbean Beach and Port Orleans French Quarter are in the same general area, so transportation time by Disney bus from either to Hollywood Studios or Magic Kingdom would be about the same. Another advantage of French Quarter, though, is that it offers easy water taxi access to the shops, restaurants and entertainment at Downtown Disney.
The French Quarter resort also features live jazz on select nights at
Scat Cat's Club, if that interests you.
I hope that helps. Please let me know if I can answer any other questions for you. Enjoy your visit with your sister!
Wilma