Hi Brian
I would recommend Pompeii, Sorrento and the Bay of Naples for a September departure. It's a fantastic tour with loads of fascinating sites, beautiful views and hopefully, still great weather. I did it in 2015 and would happily do the same itinerary again, which is rare for me. If you put 'Pompeii' into the search function at the top of the page, you'll find reviews and tips from people like me who have done the trip before which may help you to decide.
Hi Ella
I can't comment on the Christmas tour to Jersey because I haven't done it. However, and I must declare bias because I live here... 😃 , Jersey is beautiful over Christmas. The festive lights are super and we have many events going on, such as the annual Fete De Noue which includes Christmas markets and parades and a couple of local pantos. Weather wise, we often have lovely clear blue sky days but there is an equal chance of mist or fog when the sea air can feel very damp. Due to the exposed position of the Island, it can also get very windy at that time of year but if you pack layers and a waterproof jacket, you'll be fine.
Happy to help with any other questions
All the best
Mandy