I have done a couple of crusies, including a Mediterranean. We are also doing a cruise for our honeymoon! As I see it, there are infinite up-sides:
1. food 24/7. seriously…the food does not stop flowing. it’s insane. also, while one of the highlights of traveling is experiencing local food, every once in a while you just crave a burger (like on the last couple days of a 14 day cruise). The food on the ship is stuff you’re already familiar with, so it’s kind of nice that you have the option of eating adventurously in port or no-so-adventurously on the ship. And to address your question about having to eat on the ship- you certainly do NOT have to eat on the ship. In fact, many ships offer flexible dining arrangements. Really, if you view your ship as a floating hotel and not a restaurant, it is easy to justify not eating on it for all your dinnertime meals. Even if you dont eat at ALL on the ship (except for your days at sea), it’s still an incredible value just in a hotel/transportation sense.
2. no searching around for hotels (and you get to go home to the same bed every night)
3. no lugging your crap around
4. no dealing with passport stuff as you move from country to country (the cruise handles it for you)
5. you have the advantage of not getting scammed by “tour guides” who prey off of tourists. the cruises will book a tour for you through a reputable guide.
6. yet you have the freedom to go off and explore solo if you want
I have done Italy both ways- flying in, traveling around by train, and staying in hotels. It was fun, but it was really a lot of work. Being on a cruise was a lot more relaxing. It gave me more time to devote to exploring rather than coordinating logistics.
I will suggest this, though- try to spring for an outside cabin with a window or balcony. Interior rooms make you feel like a mole because they are constantly dark. it’s really hard to tell what time of day it is if you dont have a window.
Also, search around forums and stuff to see what kind of things certain cruises are known for. Princess, for example, is a mid-level line with a family emphasis. there will be lots of things to do on this cruise and you wont have any issues fitting in age-wise. Crystal, on the other hand, is higher end and suited more for older couples. If you just want to eat good cruise food and be by yourselves, this might be a good one. But you will really stick out as one of the younger couples.
Im happy to answer other questions if you have them!