Hi there!
First of all, congratulations on your upcoming Med cruise! You're gonna love it.
Here are some tips that might help you with planning your days in port.
Dubrovnik- this is a beautiful port and for many people ends up being the absolute highlight of the whole cruise. It is very easy to get to the Old Town on your own so this is the port where you can definitely save some money on shore excursions. Find more details on getting downtown here:
Getting to Dubrovnik from the port of Dubrovnik
One of the top activities to do is walk the walls of the Old Town, it will give you a chance to enjoy unforgettable views! Take your camera! It's $10 per person; entrance on your left as you enter Stradun, the main street of the Old Town.
There are plenty of monasteries, churches, palaces to see, all of them on Stradun...so you cannot miss them. The beautiful sunny Stradun and little narrow streets on its side are great for strolling around, souvenir shopping, sitting at one of the numerous cafe terraces (coffee here is even better than in Italy!) and tasting some sea food.
Food in Croatia is organic and surprises us with tastes we have long forgotten, having a lunch here is a must. Our favourite place to eat is Proto restaurant (half way down Stradun and then to the right, ask for the Post office). Down at the street level you can have a simpler menu, while up at the terrace it's all about really treating yourself...sea bas that melts in your mouth is our favourite.
One of our favourite spots in Dubrovnik is the Green market (walk to the end of Stradun, turn right to the Cathedral and then right again). It's unbelievably colourful and lively; get some dried figs or candied orange peels to snack on or take home!
The most unique and unforgettable place to have a cold drink at is the famous Buza bar which is outside the walls facing the sea. It's a bit hard to find but definitely try: enter the old town through the Pile gate, walk half way down Stradun, chose any street to the right, walk ALL THE WAY UP until you face the walls and ask the locals for it (there is just a little board saying "Cold Drinks" by a hole in the wall indicating it).
This is definitely not the day to go to the beach, you would regret it!
KUSADASI- this is gonna be one of the most eventful days of your cruise. Definitely book a tour to Ephesus through your cruise line. Everyone is going to Ephesus on that day!
Do not risk by just taking a taxi driver as the official guides are very, very informative! Even if you don't buy a tour in any other port, we recomend it here.
After the tour you will most probably be taken to one of the carpet stores. They give amazing, informative and entertaining carpet presentations and often times offer you some cheese pastry, turkish coffee and turkish tea.
Having been to those many times i am a proud owner of 3 turkish rugs myself and really learnt to appreciate them.
No matter what your budget is, i'm sure you will find a carpet for yourself! They ship them home (shipping included in the price)!
Don't take the first price, you're expected to haggle! If you get 30% off, that's great!
Tell them your budget and they will work around it.
If you're not interested in buying a rug AT ALL, simply walk out the store and don't get involved into any haggling. Once you do, chances are you will walk out with something
Our favourite place to eat is where the locals eat: a little place called Yuvvam; it's also one of Lonely Planet recommedations for authentic Turkish food. Love their meat balls, bean soup, aubergine stew...Ask anyone in Kusadasi to direct you, all the locals know it.
Although, be very careful when asking for any directions in Kusadasi: competition is so tough that business owners often lie that their place is exactly the one you are looking for. Don't trust them until you see the name sign you're looking for above the door.
Another thing...merchants here are very, very, very aggressive, ignore them if you're not interested in their goods.
I do not recomend buying gold or precious stones in Turkey. I will just say...get it in Greece if it's on your shopping list.
SANTORINI- been there only twice so I'm not a big expert but i know this: either be one of the first ones to get off the ship (tendering involved) or one of the last ones. If there are a few ships in port, lines for the cable car can be waaaay too long. If you're walking up, be ready to be sweaty and stinky when you get there.
Enjoy walking around, there are many restaurants and the shops. If you have time, you might also be able to visit Oia, a charming village 10-15 min ride away. There are car rentals at the village exit.
There are very long lines for the cable car going back so don't miss your ship!
CORFU- You've mentioned you're interested in a beach. I think Corfu is a perfect day to do it!
If you want to go both to the beach and downtown after that, if were you I would probably hire a taxi. One of the most famous beaches is Paleokastriza. There are a few beautiful secluded bays there, make sure your taxi driver takes you there.
Go downtown for a late lunch before returning to the ship. Restaurant Rex is one of the oldest and most reputable ones, just behind the colonade building on the Liston square. Try their greek salad and saganaki (fried cheese) for a starter, soft and succulent lamb for the main course (my husband would kill to have some righ now

), and baklava or fresh fruits for desert. Yummm!
Hope this helps!