I highly recommend Caroline's apartment. The space is perfect for a solo traveler. I stayed ten days and it was great for me. The neighborhood and surrounding area are very desirable and there is a ton to do. Otherwise, several metro stations are nearby so going anywhere else in Paris is very easy.
As a host, Caroline was great. I had some issues with delayed/cancelled flights and a subsequent late arrival from the U.S. I was able to communicate with her the entire time regarding those issues without a problem.