In our experience, most excursions either meet on board, or on the pier, and start from there. Can't think of any that start elsewhere.
So, I think we need a lot more specifics. 2 or 3 hour drive into town? That is usually part of the excursion. There can be a lot of driving on some all day excursions, but that is part of the excursion. Your guide/leader will be giving you information during that time.
As to what to do in a given port, beyond what interests you, start here:
https://boards.cruisecritic.com/forum/8-europe/