I am looking to buy a Select Pass. I can not decide if I need a 3 or 4 country pass. My confusion lies with my planned Rome to Munich night train that passes through Austria. Should I add Austria as my 4th country or not? What I am debating is I know it will cost an extra $50 to add the 4th country. My question is will it cost me more than that to cross? The RS website gives a range of $25-$40, but I just wanted a second opinion.
That night train's last stop in Germany is in Rosenheim, and the first stop in Italy is in Fortezza. According to German Rail, a ticket from Rosenheim to Fortezza on an EC (similar train to the CNL night train) costs 41,50€, which today is $54. If adding the 4th country costs a little less and simplifies things, I'd do it. Up-date: Sorry, I didn't read the original post closely enough. Thought you said Munich to Rome. But the same thing applies in reverse. A Fortezza to Rosenheim ticket would be required to cover the entire journey, but it looks like adding a country to your Selekt Pass would be cheaper and less complicated. And Sam has a good point(below)(which is a perfect example of how not sticking to the original question can be helpful). You should price out all the legs to see if a rail pass is really your best option. In many cases, you can get a complete (rail and accommodations) advance purchase ticket online from the Bahn for not much more than the price of accommodations alone (called a reservation fee) that you would pay in addition to a rail pass.
As is often posted on this sight, price out your itinerary in advance on each country's rail site to see if a rail pass really saves any money. With the rail pass you're always traveling first class if you're over 25, so you'll be paying a premium for that. Italy is especially cost effective to purchase point-to-point tickets.