I voted for "Other Europe", since Slovenia is neither Western or Eastern Europe. It's somewhere in the middle :)
Unless we speak colloquially, then there's an infinite number of groups to qualify. The OP should use some reference to choose categories ( http://news.ycombinator.com/item?id=2147290 ), his are a bit strange and subjective.
Compare that to the amount of options for the US with its 220 mio population.
I'd propose a schema like this: http://commons.wikimedia.org/wiki/File:Europe_subregion_map_...