IMO if your desire is the mediterranean, choose one general area and stay. That area of the world is so beautiful and has so much history you'll regret doing just a short stay in each place if you're bouncing around a whole lot of ports.
I have a personal bias towards Portugal. You can do the white sand beaches of the south for a resort-ish vacation, Lisboa/Cascais/Sintra for the big city with shopping, historic castles, museums, etc, or the Dao and Douro valleys/Oporto/Castel Branco for the historic winemaking areas. Or you can do a couple weeks and do it all.
I've also done a tour around Spain; Toledo, Granada, Cordoba, Sevilla, Barcelona, Madrid.
IMO it should be every American's duty to visit the beaches of Normandy in northern France.
I've also done a road trip from Munich--Vienna--Linz--Salzburg--Budapest--Prague. One of the coolest trips I've ever done, we visited the Eagle's Nest and Neuschwanstein Castle.
This is all coming from a history nut though, I wanted to see a lot of the Moorish occupation of Iberia and the fallout of WWII.