Congratulations on your pending marriage and your wondeful honeymoon cruise.
I cannot offer any specific advice on the ports you will be visiting. However, some general knowledge that may be of help.
(1) Spend a lot of time researching where you are going to be at on the internet. Google every single port. You will quickly find out what is or is not of interest to you.
(2) There is a 'comfort level' in cruise line excursions - if there is some kind of a problem that could cause you to be late getting back to the ship, the ship will wait for you. Given the same senerio with a private tour or do-it-yourself tour, the ship will not wait for you.
(3) For Greece and the Greek Isles, check out Greece and Greek Isles
I have found it to be extremely helpful in planning our June Med cruise.
(4) While on Google, use the google maps (satellite or hybrid views) for each port. Gives you very good insight about each port city.
Have a great honeymoon and marriage.