Walk to the city center it is a half a km away from the dock. MSC charges 6 Euro for a bus ride there, and won't help you find your way if you don't want to pay. Not much to see in Bari as you are only stopping to on load more passengers. St. Nicholas is buried in an old church. That is about it besides eating Gelato.
Skip the MSC excursion here for sure. There is a company that runs buses for 10 Euro. MSC bus ride is 43 to the same place. Olympia is cool, but you really don't have time to see much since it is so far away. Tip: you can't get a Gyro in Olympia before noon. I was disappointed!
Amazing town. We skipped the excursion and walked since we needed to burn some cruise calories. We were able to walk across the bridge to Topkapi, Haggai Sophia, the Blue Mosque, Grand Bazaar, the spice market and Starbucks with ease in the time we had in port. Saved a ton in cab fare. Be warned the rugs in the Grand Bazaar are over priced. They will start at $10,000 so you feel like you got a great deal when you buy it for $1200. In reality I can get the EXACT same rug in Adana, Turkey for $400. Made in the same factory. They sell you a wool rug for what you should be getting a silk rug for. My wife was very happy to be able to go in the Blue Mosque. Take a scarf to cover your head if you are female though. They will loan you one if you don't have one, but I don't know about using someone elses head cover. Blue Mosque is free, but Topkapi and Haggai Sophia are both 20 TL to get in (about $4 USD). Great port.
Great city also. Skip the MSC tour since there really isn't much to see. Again you will be forced to pay 10 Euro to get to the city on the MSC shuttle. Do it though as Dubrovnik is amazing and a must see. The Gelato store as you first enter the city is amazing and the guys make a show out of scooping the ice cream. I will definitely be going back since we enjoyed the coastal town so much.