Suggest you go to a different website that offers opinions and experience of what to do in each port. go to boards dot cruisecritic dot com and then scroll down to the Ports of Call section and click on Europe.
Shore excursions on any cruise line are expensive for what you get and most can be done by yourselves at a fraction of the cost but do remember to allow plenty of time for returning to ship as it will not wait for you if you are late. Have sailed with NCL but did not do their trips as I didn't think them value for money. Can't comment on Paris, but Florence and Pisa are easily accessable from Livorno and trains in Italy seem to run very much to schedule. Research on the web and you should be able to plan shore excursions yourself at a fraction of the cost. If Civitivechia is on your itinery there is an excellent train service from there to Rome costing only 9 Euros ((last years price), and you can easily walk to the train station from the dock area.
I would take the excursion on this cruise - if you were just visting an island - you could do it independently - ie many taxi waiting there outside the port with a good price - NCL do not know -cunard yes! - john robinson - leiceste.
Go to the excursion talks and also talk to the person giving advise on where to shop in eacport of call, they are usually stationed in the reception area each evening.
You can then decide if you want to do your own thing,in the main NCL excusions are good value as they are priced in dollers and with the exchange rate approx two to one they are good.
I don't know about Paris but the Florance trip is best with the excursion as it give you the most time in the city and you will need as much as possible it is fantastic.
We have sailed with ncl 3 times and like most other cruise lines tend to over charge for organised tours however for the more distant destinations from the cruise terminal it may be better to prebook but for discovering the port of calls its usually much better to use the open top bus tours available close to the ships terminal or in more remote areas join another couple and seek out local taxis who are always waiting nearby and are a wealth of knowledge. this is much cheaper and a more personal servic.
We have been to Livorno on a previous cruise, I am not sure about the train to Florence, we used the train to go to Pisa which was a very good and regular service. When we arrived into Livorno there were lots of Taxis at the port and they had the price for a journey to Florence, it was more expensive than the cost of the Cruise Lines excursion. The taxis were very expensive. The port ran a free transfer bus into the town and we got a bus to the train station which was very easy to do. As another person has mentioned, look at cruisecritc.com they have an excellent board which has lots of information regarding ports of call , it is also good for information on the various cruise companies and lots of other aspects of cruising, you have to register to be able to look at all areas of the site, there is no charge to register. If you decide to do your own thing , make sure you allow plenty of time to get back in, the ship will not wait if you are late. ( they only wait for customers on the organised excursions .
Just came back from cruise on ncl jewel dont know about paris but cheaper excursions by your self. in livorno train station is very close and cheap all english speaking 20 euros is all it cost for two adults to pisa dont have to pay for children pisa 15 minutes 0n train florence about hour and half. we did all our own excursions and paid about quarter of the cost asked for by NCL also you have more control over the length of your excursions.
We did NCL to New York two years ago. The trips arent always value for money. You need to decide what you want to do then do some homework. Barcelona you can do on your own. If you have an ipod download a walking tour from the internet.There are loads about and you can do this at your own pace. The ship docks about 30 mins walk from the town, but there is a shuttle bus from the port at a minimal cost. There is stacks to do in Barcelona. lovely fish market and Las Ramblas.
Florence I would recommend getting a trip for. NCL may do a coach trip where you can get dropped off and picked up so you have time to do your own thing. This is worth the money.
Not sure how long it would take to get to Paris from Le Havre never done that but you could probably get a train from there to Honfleur, or Arromanches (D D beaches) well worth the trip.
Good luck and enjoy the cruise!