That depends on what city you will be travelling in.

Where are you planning to travel?

The S-bahn is included in our pass network in Vienna, Innsbruck, Germany, and Zurich. Please remember that you need to activate a travel day and add the relevant journey before boarding the train. You can find a full list of participating carriers here. 

In Bern, Switzerland, you can use Interrail/Eurail on the S-Bahn routes that are run by BLS. On the S-Bahn routes run by RBS you get a discount of 50%.

Also in Copenhagen and Oslo. Austria also has S-bah networks around other large cities, as Linz/Graz/Salzburg, all by OeBB and thus included-except that SOME lines near Graz are not!=not OeBB but GKB.

In fact about the only exception (but it is not even named as such there) is STOckholm (pendeltag).

Many more cities have now also started to rename their local busy lines around big cities to  S+nr-incl Budapest. These would not confirm to the strict standards that in Germany are used to distinguish this.

IF you have a pass with passdays-it will not be worth it to use it for just a few short trips in the city-buy local tickets or daypass. Most often it is integrated fare with the local bustrammetro.