Hi Louise. Welcome to the JY Forum. :)
Sorrento is my old stamping ground, although I haven't been for many years, and never with JY. What can I say? It has always been busy there, but the scenery is wonderful. If you want to be on the coast then I hope that JY do the Rome/Sorrento trip next year.
As for Croatia?
I haven't been to Makarska for many years, but the scenery is stunning, it's still relatively inexpensive in Croatia and there are lots of good walks. I did the Istrian Riviera trip last year, and that is a good value holiday which I can personally recommend. The hotel is right on the Lungomare and you literally can walk miles by the sea.
I was on the Dubrovnik Rivera trip this May, and we did have some problems with the hotel which I certainly hope will be ironed out for next year. Cavtat where the hotel is, is a beautiful spot and I would certainly recommend it for a base. Again it is a good value holiday with many great excursions.
If you want to know more, I am more than happy to help with any queries if I can.