On our recent foray on Harmony we did each pack a beach towel in our carry on as it was only my second cruise (first back in 1999) and the kids' first so I wasn't sure how quickly towels would be available. As it turns out, we rather enjoyed not having to check in/out the ship's towels and having a little larger and maybe plusher towel. That said, you had to make sure it was laid out to dry and and other factors. Bottom line is personal choice and maybe try one way then another to see what you prefer. The process for towel distribution and return was rather smooth from observation.