We Have Done Both and
have even set off on our own, relying on local transport -- taxis, buses, the odd ferry or two. We got so relaxed that we left the ship in one port with no idea of when it was scheduled to sail! Fortunately, there were plenty of other cruisers around to ask. Everyone always talks about getting back to the ship on time (a valid concern) but no one ever talks about getting to the tours you book on your own on time. Delays in getting into port, weather, tendering -- all these can affect your ability to meet up with your tour at the appropriate time -- especially if the tour you book on your own is not one of the cruise ship tours. Do some research on line first. Sometimes there are savings, sometimes not.