We spent an extra day after the cruise in Athens. It was easy to get from the port to the city using the Metro (2 or 3 Euros). We stayed at the Hotel Plaka Athens which was within a few blocks of the Monastiraki Metro stop. It is a nice hotel with a rooftop bar (great view of the Acropolis) in a convenient area for sightseeing. I would recommend it.
We did sightseeing on our own using several Rick Steves MP3 tours. Just be sure to double-check the open hours of each place you want to go online right before you go. The open hours were different from those I found in a recent guidebook and from those posted in the hotel. We almost missed seeing the Agora because it closed at 3pm rather than 7:30 pm as our guidebook had stated!
Using Metro to get to/from Piraeus and to/from the Airport is easy and inexpensive but BE VIGILANT! You will be constantly warned that thieves and pickpockets are everywhere and it's true.
This is an easy port to see on your own. Begin by getting some Turkish lira from one of the many ATMs located on the street next to the port area. We got ours from an ATM next to a bank and then went inside the bank to exchange the large bills for some smaller ones--necessary if you plan to buy tram tickets.
The tram, with a stop just a couple blocks from the port area exit, costs 3 TL and takes you right to Sultanamet Square (or anyplace else you are likely to go). In our nearly 2 days in Istanbul, we were able to do leisurely tours of Suleyman Mosque, the Blue Mosque, Hagia Sophia, and Topkapi Palace, again using the Rick Steves free MP3 tour. (We are not shoppers, so we avoided the Grand Bazaar and the Spice Bazaar, but he's got tours of those too.)
Suleyman Mosque was a treat for us. It's not difficult to find, but is somewhat "off the beaten track". Because it's not near the other main tourist attractions, there are very few visitors there and you can actually experience what a mosque is like--unlike our experience in the Blue Mosque. We were disappointed that the buildings housing the tombs of Suleyman and his wife were not open, but you can see them through the windows. I would highly recommend a visit here!
We arranged a private tour before our cruise with Odessa Walks and I would highly recommend this company. We did a 3-hour Walking Tour of the Highlights of Odessa and our guide, Olga, took us everywhere in the Old City! This was followed by a tour with Olga to the Catacombs just outside of Odessa which was fascinating. Olga gave us the "unofficial" version after our "official" tour. The Odessa Walks offers several different tours for cruise passengers which fit into the ship's schedule and they cater to small groups. Since nobody else from the Pacific Princess had scheduled a City Highlights or Catacombs tour, we had Olga all to ourselves!
We'd visited Rome previously, but enjoyed a couple of days sightseeing here before our cruise. It was easy to get around by foot and to use the train to get from the Airport and to the ship in Civitiveccia. We stayed at the Aberdeen Hotel (within walking distance of Termini Station) and would highly recommend it--great staff!
We did a self-guided tour to Herculaneu and Pompeii.
The most difficult part was just getting from the ship to the train station since the Princess shuttle buses, which would have taken us to the train station, did not begin operating until 10am and we needed to be on the train NLT 9am in order to see both Herculaneum and Pompeii (which we had both visited before.) It's a long uphill walk to the train station, so a group of us overpaid a taxi driver 20 euros to take us to there.
It was easy to buy the train ticket and the train was good, but crowded with local commuters. The ruins of Herculaneum are located just a few blocks from the train station and can be toured in around an hour. The ruins of Pompeii are located right next to the train station. Buy your ticket (which covers both Herculaneum and Pompeii) online before you go or in Herculaneum because the line to buy tickets in Pompeii can be quite long. If you already have your ticket, you can by-pass this line. We used the Rick Steves self-guided tour (available in his guidebook, as a free MP3 download or as a free I-phone app) and thought it was a great tour. We spent about 2 hours in Pompeii.
Upon our return to Sorrento, we walked back to the ship--a lot of stairs DOWN, but not a long walk.
We actually did not see Yalta, but did the ship's excursion to Sevastopol. Due to the distance from Yalta and the short amount of time in port, I would not do a private tour to Sevastopol. Due to problems with the ship's engines, we ended up having to be tendered at Yalta. This, combined with the terrible traffic to/from Sevastopol, meant that any private tour would have had to have been shortened in order to get us back to the ship in time. Because we were on a ship's tour, we were able to see everything and then come back late and have a tender waiting for us.
The tour of the submarine base in Balaclava was interesting, but there's not a whole lot to see inside. The stop at the seaside park should have been changed to a stop at the site of the Charge of the Light Brigade--there's not much to see in that park. The Panorama museum was interesting, but don't let them rush you--take your time and see the painting on both levels! The lunch was best we had on the 3 ship's excursions we did--it included both champagne and vodka and the food was delicious.