Two med cruises here

We sailed out of Civitavecchia (Rome) both times.

it should be seen as a taster of the Med.

On our honeymoon, we did the eastern med which was Italy, Greece, and Croatia. I think we got a nice taste of the Greek Isles. Dubrovnik was incredible. As others have noted, you dont really get depth on a cruise, but some advantages acrue including not having to figure out dining, and not having to pack.

I think a cruiseline like Holland America is great for this sort of itinerary. Their ships aren't huge. Their food is pretty good, and their service stand is high. And since you will probably want to spend the vast majority of your time in the ports and not on the ship, having crazy ammenities is largely unnecessary.