National geographic highlights Montenegro as one of "the best spring trips of 2017". The following is an excerpt of an article posted by National Geographic by Maryellen Kennedy Duckett. http://www.nationalgeographic.com/travel/best-trips/best-spring-trips-2017/
Eastern Europe by Balkan Flexipass
The scenery on this trip is just as stunning as Switzerland's for half the price.
For first-class vistas on a bare-bones budget, ride mainly by rail (partly by bus) from Serbia to the Adriatic coast. The original train route—completed in 1976 and undergoing its first major upgrade—dramatically winds through mountains and briefly passes through Bosnia and Herzegovina on its way from Belgrade, Serbia, to Bar, Montenegro. Due to construction, the first leg of the 10-hour (one-way) trip currently is by bus. To add more train travel, buy a Rail Europe Balkan Flexipass (starting at $108) for three, five, seven, 10, or 15 days of unlimited rides on national rail networks in Bulgaria, Greece, Montenegro, Macedonia, Romania, Serbia, Bosnia and Herzegovina, and Turkey.