Monaco - its not a port but rather its a country! If you are tendering into Monte Carlo you will be right in the city. If you are docking somewhere outside the city (Villafrance, etc) you will need to take a bus, taxi, or train.
Mallorca-You will generally dock at a pier which is a couple of miles from town. You can easily get into town by using a local bus or a taxi. Personally, we like Mallorca for its beaches (this is why many Germans and Brits go there on vacation). There is a good long sandy beach located on the coastline adjacent to the airport. We get there by taking a bus from the pier into town and transferring to another bus that runs parallel to the beach (2 blocks inland).
Palermo - You will dock in the port that is right on the edge of the city. It is possible to walk into the center of town from the port or you can use a taxi.