I assume you're proposing a non-Disney Med cruise, as they don't go to Greece?
I did a trip this summer that was an
ABD *on* a Med cruise. If you like to cruise, it could be a great option.
Personally, I'm not the hugest cruising fan. While it is fabulous to get to so many different, fascinating places without having to pack & unpack over & over again, I find that I like spending more time in a place than you get to do on a cruise. While I truly enjoyed the ABD/
DCL cruise, I found it really hard to leave these places & go back on the ship in the middle of the afternoon some days, and not spend the evening/dinner/etc, in the middle of where I was traveling to. I've definitely found that, for me, I much prefer a land-based trip. You really get immersed in the locale better that way.
Also, sometimes seeing where you are traveling between destinations (even if it's by bus) can be preferable to traveling there while you sleep, in the dark.
And I've found that ABD puts together some really fabulous land-based trips. I don't think you can do wrong signing up for one.
Obviously, this is my personal opinion, and my personal experience.
Sayhello