In most German cities rail passes are also valid on the S-Bahn. But usually you’ll have to buy the regular public transport tickets, though sometimes they have week passes or something that work out cheaper.

Eurail is not valid for virtually any local transport as far as I’m aware. Check with the tourist info kiosk wherever you arrive and they can tell you about deals on metro/train tickets (like 3-day passes). Usually they’re not very good deals though.

I would just buy all of the city transportaion tickets when you get to the city. I like to buy an all-day pass on the tube or metro, depending on what city you are in. This lets you go just about anywhere in the city very quickly. If you are in a smaller city just walk. Even in some larger cities it’s nice to just walk. You end up finding things that you never expected to see and you get to see a lot of neat places and things.

Eurail passes are good on S-bahn in some German cities, Zurich and Vienna but not the U-bahn, which is more what you’d use to get from place to place within a city. For the most part, S-bahn is good for getting to/from the suburbs, but not all that convenient for getting around within a city.

Railpass is also good on part of the RER in Paris, but not through the center of the city. I think it’s honored between CDG and Gare du Nord, but not past there. It’s honored on part of DART in Dublin — at least you can get from the ferry port to one of the Dublin train stations.

In Germany rail passes are valid on ALL S-Bahn trains, because they are all run by the German Railways, as opposed to U-Bahns/Trams run by local transportation companies.
As far I as recall in Paris rail passes are indeed valid on part of RER. However using it is involves a hasle of having an agent to let you in/out through the turnstiles.

In Austria, Germany and Switzerland rail passes are valid on ALL S-Bahn trains. Also in Copenhagen (S-Tog).
How useful they are for travelling around the cities differs. They are just an integrated part of the local public transport networks. And as a normal local public transport tickets covers all local public transport (local trains, S-Bahn, U-Bahn, trams, buses) the maps don’t differ between them – for the average user the difference is of no importance.
[url=‘http://www.s-bahn-berlin.de/pdf/s_bahn_netz.pdf’]Berlin S-Bahn and U-Bahn network[/url]
With a rail pass you could only use the S-Bahn lines (S<number&gt and the RB and RE lines in the outskirts (thin red or black lines). Not the U-Bahn lines [U<number]. The tram and bus lines are not shown on this map. The map is not really on scale. To give you an idea: the circumreference of the S-Bahn ring which defines the central zone A (white) is 39 km.

Some price examples:

A single ticket for local public transport in Berlin is EUR 2,00. A day ticket for Berlin (zones A (white) and B (grey)) is EUR 5,60. A 7-day ticket EUR 24,30.

A single ticket from Munich Airport (which is not in Munich) to Munich is EUR 8,80. A day ticket for the whole [url=‘http://www.mvv-muenchen.de/en/index.html’]MVV[/url] network (Munich and surroundings) is EUR 9,00. Just 0,20 more than a single ticket – thus day tickets can be sometimes really good deals. A day ticket for inner (=touristic interesting) Munich is EUR 4,50.

what about using a bike to get around the cities? would the bikes be easy to take on the train? to use in another city