That's exactly the attitude you should have, you want to see as much as possible.
There are several 7 days itineraries and a 9 day but they don't offer a lot of variety IMHO.
Here's how to find them:
http://www.vacationstogo.com/custom.cfm
Choose a region - Med
From Sep 2012 to Sep 2012
Minimum nights - Max nights first try 7 to 9 then try 10 to 11 which gives you a lot more choices
I narrowed down the cruise lines to Celebrity, Holland America and Princess ... the others are either low end or high end or avoid (MSC, etc.)
You can also select a budget, certain islands you want to visit, islands to exclude, departure port, etc.
We've never been on a Med cruise but my ideal itinerary would include Italy, Istanbul, Turkey and lots of Greece.