What Pal says is exactly right. Put me down for another who enjoyed overnighting in San Marino. When

No - but close to it at Rimini - take a train to Rimini then frequent local buses - dirt cheap - to San Marino itself - an old train line once went up there but has been pulled up long ago - the buses I am sure do not accept Eurailpasses but again are dirt cheap - go to www.trenitalia.com and put in Rome and Rimini for the best rail connections - lots of trains but with a pass you do need to make a seat reservation before boarding on all but regional and IC trains - costing 10 euros per seat per train - so if you have to change like probably then it adds up so try to get as direct trains as possible.
I loved San Marino and stayed overnight there - some folks do not like it because it is in the town center in daytime very very crowded with tourists - many Italians day tripping in to buy cheaper booze and cigarettes and other taxed-lower good. but if you get away from the commercial tourist hubbub you have a sweet typical Italian hill town, topped by old fortresses.
checking timetables on www.bahn.de - German railways web site I use for all European trains indicates San Marino may now have rail service - or it is confusing S Marino with another S Marino. In any case easy to get to by Eurailpass either all by train or a cheap bus ride from a nearby train station.
craigs list motorcycle sales and los angeles What Pal says is exactly right. Put me down for another who enjoyed overnighting in San Marino. When the day trip folks leave the city transforms. Prices are low compared to surrounding Italy. One thing though, it is quite hilly, so if that is a problem for you, you need to be aware before you go.