We did a Western Med one last year on Norwegian Epic, absolutely the best holiday i've ever been on, waking up in a different country every day, and if you plan beforehand you have plenty of time to see and do everything you want.
Food was incredible and I think there were 15 different restraunts in total, some you had to pay an extra for but well worth it (Tepanyaki etc).
The ship also had loads of different bars, clubs, theatre, ice bar, casino etc so you never felt bored, saying that, when you have spent all day in Rome then got back on and gone for dinner, most nights we were bollocksed!
Also with NCL it is classed as free style dining so you don't ave formal nights, in the A'la Carte restraunts you can just wear a pair of jeans and a shirt etc which I liked as I didn't have to make any more effort than I normally would going out for a meal.
Met some great people as well, we are in our late 20's but met a few couples from all over (Brisbane, Texas etc) who we keep in touch with still.