We have returned for land trips to port stops we enjoyed so much that we wanted to return.
Three weeks in Sicily, ten days on Malta, numerous land trips to Italy, Greece and Turkey, etc. Earlier in the summer we had a week on Madeira as part of our Portugal trip.
Now retired, our habit is to pick up last minute cruises while we are on extended land trips.
You sound like me with regard to travel; I have only done three cruises, but they were strategic to sample an area and then go back for a longer time if I like the area (Greece - Santorini and other islands - Naxos and Paros my favorites now - no more Santorini; Caribbean - probably not return). My first cruise was an Alaskan one on Holland America. It was a great cruise. Had an inner cabin and the only packaged excursion we did was a hike near a glacier. All other port stops I had planned a separate itinerary by doing research from cruise critic and other sites with regard to what had the most value for the amount of time one had in port.
The second cruise was an eastern Mediterranean - Holland America again. That was a great cruise, too. One of the best parts of that cruise was we stopped in the port near Ephesus and watched as many people took a loaded bus to the Roman ruins. We walked to the center of town and picked up a local van for about $3 each and took that to the exit of the ruins which is also an entrance- walked up through the ruins, out to a very nice and wide sidewalk that was lined by palm trees and walked to the town near the ruins where we had a nice lunch and picked up another van back to the port town; walked through the port town looking at stuff to buy, hit a Turkish Bath (Hammam), walked back to the dock, sat at a bar and had a few drinks and watched as the busses disgorged their passengers for embarking on the ship. We waited until about 20 minutes before the deadline and walked leisurely back onto the ship. My then husband was amazed and laughed at how my planning had allowed us to do and see so much more than most; he had related our day to many and they were amazed, too. We saved probably 75-80% of what all of the people who took the tour did.
We did something similar in Dubrovnik, however, we had been there before and we met a dear friend of mine there at a very nice restaurant. That involved a bit of walking to/from the port. One does need to be mobile as the ports tend to be a bit away from the city centers or areas of possible interest.
However, we've found that the prices for the tours go down at least 25% to 50% if you just walk off the boat and look at what is available. Moreover, there are travel package operators like Viator that cater to this crowd. I've even used Viator when in an area for a day package - I did this in the Baltics. I've even become cheaper and looked at who Viator is outsourcing the package to for the tours and gone directly to their websites or emails and at times have gotten better prices; did that in London, too. If you know how the system works you can go to the source and save money for experiences or stuff.
For the OP, we bought our cruises (the last one was a Caribbean which I did not like as it seemed like groundhog day; I could not tell the difference between the islands and I don't drink a lot, so wasn't a big participant in that part of the culture - loved the snorkeling, when we could find places with the pretty fish) on one of the cruise consolidator sites; we never bought a drink package; we tended to eat at the buffet for all meals (we did the restaurant one night); we did not buy any packages for drinks or otherwise; we had an indoor cabin as we spent most of our time either walking around the boat or in port; I found out the reception desk had a library of DVDs one could watch in their cabin, so for forced downtime, I watched those or read or did some other activity (I crochet); we paid for the tips afterwards via credit card; we played the little games for prizes - won a Holland America Sweatshirt that the crew wears- that was interesting as there was a group who knew each other a lot from cruising a lot and they did these games as well - usually sports oriented; we never gambled; we were first off and last on the boat during port days as we used those for sampling the different ports and surrounding areas; we did go see some of the shows they had every evening on the boat. There are very different people on cruises who cruise for very different reasons - we also would talk to our fellow cruise mates to meet them and swap interesting stories or tips.
So, lastly, what is a thread for if it isn't derailed or redirected in one way or another. My next big trip is to Morocco: Marrakesh, Fez, the Atlas Mountains and a camp night in the desert. I also am tentatively planning a three day hike along the UK Northumberland coast; I did a three day hike along Hadrian's Wall this summer (the hard part in the middle
) and fell in love with Northumberland. I also did a long weekend in Liverpool and The Wirral - wow - gorgeous places and such friendly people. Plus the pub I found, The Plasterer's Arms, was great - had a blast -went two times and suspect if I went back again would become one of the regulars.
Plan to hike the last 100km of the Santiago de Compistela next spring; hope to take a tour to Samarkand; and have a tentative hiking trip planned to Patagonia. Will also do a few ski trips - may fly to Sweden to ski there and add a country to my ski bucket list. Also want to ski Japan....
Best wishes to the OP and the cruise info they are receiving here - lot of good tips to maximize the value to them of the experience.