Destinations are why I cruise so getting off the boat is a priority and we've done cruise line tours, private tours and self-guided. The choice depends on location, length of the stop, what's on offer and what I want to see. In some places I want and am prepared to pay extra for the security of a tour operator who has been vetted by the cruise line and who the boat will wait for if we are delayed. Elsewhere I'm comfortable with a local hire or just striking out on my own.
Regardless of which route is chosen I don't fret about cost. If I've come this far and paid this much already it makes no sense to nickel and dime over the tour costs. Seeing the things I want to see is the reason I got on the boat in the first place.