Naples was very busy and we took a ships tour. Barcelona you can do on your own, most ships have a bus to the Ramblas area and at the top of the Ramblas you can get on the tour bus that takes you around Barcelona( they have 3 different routes) and you can get off and on whenever you want. The price is reasonable, i think it was 17 euro for unlimted rides all day this past summer. In Marseilles we used Catherine at provence-travel and she was great, she did everything my wife asked her to do and more. S he was a wonderful tour guide.
there are many companies that do reputable tours in Europe , we were lucky to use driverinrome.com for our tour in Italy. They have contacts with the ship so in case of any delays thet can call poort agent to hold the ship until you get back.They also guarantee that if the ship does not make it to port they will not charge your cc .Their website is www.driverinrome.com
Hope this helps!!!
Ditto driverinrome -- we used them for Florence, Rome, and Naples -- they will get you back to the ship -- its very reasonable compared to ship's tours -- plus you will see tons more, and won't be exhausted from walking where the busses drop you off -- the small vehicles can drop you right off at the museums, etc. -- see what you want to see,