Ok, since it has been days with no answers...

Slovenia was the northernmost part of Yugoslavia, bordering both Austria and Hungary.

During the age of Austro-Hungary, the territory of today's Slovenia was an averagely developed part of Austro Hungary. Shortest lines of access to the Adriatic sea for Austria and Hungary go through Slovenia and western Croatia. The major ports of northern Adriatic - Trst/Trieste and Koper/Capodistria are inhabited by Slovenians. Local industry was developped.

So, when Austro-Hungary split up, the slavic Slovenia eventually wound up as part of SHS, then SHS, then Yugoslavia. As an averagely developped part of Austro-Hungary, it was now suddenly the most developed part of Yugoslavia. Slovenia gained access to Yugoslav markets and benefitted from protective tariffs, establishing significant trademarks in the Yugoslav market.

During the Yugoslav period, Slovenia kept this edge. So, when Yugoslavia ended, Slovenia started off with a head start.

Second, Slovenia got away from Yugoslavia untouched - the war only lasted for a few days. Partly, this was due to the fact that Croatia geographically separated Slovenia from Serbia, but to be honest, Slovenia was not really part of the Serbian main influence areas, so... the Yugoslav army didn't really try too hard when Slovenian territorial defence force showed real resistance.

So, no war devastation, but, more importantly, Slovenians did not really manage to make any enemies. They didn't participate in the genocides of the wars (ok, they did screw some people in a more administrative way, the Erasure), but in comparison to the horrors of what went down further south...

Since, Slovenia has generally managed to keep reasonably good relations with the Balkans, and has profitted from this greatly as an.. "entry point" for Balkan markets.

Lastly, Slovenians were led towards independence by the previous local authorities. So, former communists made the transition far more smooth than it could be. No purges and similar. This has kept the politics more moderate, stabilizing the country, compared to the turmoild due south. Also, Slovenian economic transition, while far from flawless, didn't take all the western advice that did so much harm to some other transitioning countries.

So, essentially, Slovenia stayed boring, and boredom is valued in times of turmoil.