Try using the railsaver tool here — under the “booking” tab at the top of the page. That should give you a good estimate of “regular” prices and whether or not buying a railpass is a good deal. For exact pricing and to look for special fares for specific dates and times try www.thalys.com for Paris/Amsterdam, www.Eurostar.com for London to Paris or Amsterdam www.sncf.com for trains in France and www.trenitalia.com for trains in Italy.

I use 5 euros per day as a generous estimate of what you’ll spend on local transportation. The biggest cost is usually getting between the airport and city center on arrival and departure days. Other days you probably won’t average the full 5 euros.

You might give a look at
http://www.seat61.co…
He has a wealth of information on train travel; you can sometimes save quite a bit on a given train by buying your ticket early, or on special days. One advantage of train travel is that the stations are downtown, so you don’t have to pay extra for transportation from the airport to downtown.

As for local transportation, we bought carnets (a strip of tickets that costs less than individual tickets) for the metro. In Amsterdam, walking was easier than taking local transportation. Rome was less compact, but everything we wanted to see was in a relatively small area and we just walked. Venice is quite compact and walking is the best way to get around (and to get lost), but we did buy a ticket to ride on the vaporetto’s as they give a good look at the grand canal, and are the only way to get to some of the other islands, such as Murano and Burano, which are well worth visiting. The gondola’s are really expensive, but there is one place where they just take you across the grand canal, or back, for pocket change; but it is very like a cattle car and they herd you on and off, and complain if you sit down; I just sat down anyway as my legs have become pretty unsteady and I didn’t want to take an inadvertent swim.