Great second cruise, Burt! Our first cruise was a 7-day in the Med., then our second cruise was another 7-day in the Med., then our third cruise was a 12-day in the Med. on SPLENDOR (see where this is going???). Splendor is a great ship. You've got a great itinerary. Please note, though, that you'll need a vacation when you get back - those Med. cruises are soooooo port intensive that you'll be worn out.
We did a 12-Med. in May on Millie and did some of the ports you'll be visiting. I'd highly recommend going over to cruisecritic.com and checking out their RCCL meet and mingle - and their European threads as there are groups forming that are looking for others to share private tours. That's what we did this time. If you need more info - contact me at my e-mail address - but give cruisecritic.com a try - their Royal Carib. and Celebrity boards are great at helping folks pull together private tours. As well as giving perspectives on the ship's tours.
Our first time in Venice we purchased the ship's tour (Splendor!) of the waterways of Venice: it gave us a nice perspective of what we wanted to see on our own - and how to get there. It's an easy city to navigate - and if you think you are lost just look for signs pointing toward "San Marco" and/or "Riealto" - two main points in the city. It's just a great city for walking.
Mykonos: ship will probably provide a free shuttle into Mykonos town. Again - a great walking town - can't get lost. I just didn't see a need for a tour there - just find the windmills and "Old Venice" - both areas are together overlooking the Med. - absolutely beautiful place for photos and to enjoy a nice lunch.
Croatia: Beautiful! Unfortunately, I was ill in the morning and had to pass on a tour of the country side we had booked. But we did take the ship's transportation into the old city and while I was unable to climb and walk the walls of the city (darned!) we did enjoy just walking along and enjoying the beautiful scenery. It's just a beautiful stop.
Athens was okay: we took a ship's 1/2 day tour of the city and were disappointed. Spent hour or two in the "plaka" shopping and eating before returning to the ship.
Sorry to see that Santorini isn't on your itinerary: it's to die for! Oia at sunset is just (no words to describe).
You'lll have a great time - and e-mail me if you have other questions.
Also did 12 days on Millie and sailing out of Venice was a highlight! Be sure to be on deck early to grab a good spot becuase it is special.
Aside from that cruise I have done others in the Med but dont have much to add to the first reply you got.
However if I can help - I gladly will.
Croatia - Dubrovnik. The ships shuttle takes you to the Old City - which is full of character but small. However we were happy doing the walls (hope its cooler for you) and milling around the old city. Apparently the ships excursion alongthe coast is very beautiful.
In Athens - which we had done before on a land based holiday - we used the metro. A comfortable walk from the Ship. And we went back to the Plaka and shopped. In the Plaka there is also a little tourist bus/train that takes you to a few sites. Nothing major but a welcome respite for tired feet.
Of course you have to do the Acropolis and depending on how much of a history buff you are - u may want a guide.
Mykonos - very walkable. Tho I am sure we only saw a v small portion of it. However time was limited on our cruise.
Rhodes - LOVED the old town. And sounds like you will be one of the scooter brigade - hire one of the yellow jobbies and tour the island. I cannot coordinate scooters and the such like - so I stuck to the old city - happily.
Venice - you dont need any tours. Take the water busses - walk - have a guide book - and a great time.