One of the best kept, dirty-little-secrets of European travel is that rail passes are no long the great deal they once were. As long as you stick to the run-of-the-mill trains, you're ok, but don't try to use one of the special trains.
In Italy, the passholder surcharge for using a EuroStar, and on many lines that is about all there is except very slow regional trains, is almost half of the full fare.
Similarly, try to get a reservation for a night train. Sorry Charlie. None of the national rail companies sell the "reservations" online any longer. Of course you can always wait until you get to Europe and try to reserve sleeping accommodations then, but they will probably all be gobbled up by the Europeans by then.
For a single night train reservation, RailEurope might be your best source. More than one - you're probably better off with Euraide. Still, you're paying a lot extra over the cost that Europeans pay.
There are a lot of special fares out there on national rail company websites for non-railpass holders. CityNightLine, a German Rail subsidiary, offers great Europa-Spezial fares, rail and accommodations, often for not much more than the passholder fare.