Letting Yugoslavia survive...
1. To make it happen, I only see one possibility:
Hard to imagine afterwards, but there existed actually sane politicians in all parts of Yugoslavia around 1990, pity is they didn't prevail.
Actually, it is not too hard to imagine that Yugoslavia became a federal democracy in the late 1980s - the framwork for federalism was already laid out in the Yugo consitution. It would just have to survive democratic reforms, whereas in OTL populist nationalists wrecked the state.
I rule out a monarchical alternative; it didn't work well the first time around and chances are too high that the head of state would always be seen as a Serb (accent, orthodox confession, lineage), whereas a democratically-elected president could stem from any region. Actually, the 1980s constitution replaced the president on a yearly base, handing the post around through Yugoslavia.
There is another problem with the federalism in the existing 1980s constitution. It guaranteed each republic the right to secede! Now how funny is that?
Communism is a no-no post-1989. It only makes economical problems worse and encourages the West to support any fractions advocating a break-up.
2. Possible PODs...
...have a strong personality to play the role of Tito after 1980. He (heck , maybe she) would have to be able to rally the forces of sanity throughout Yugoslavia, promoting democracy, cultural autonomy and wealth through liberalization.
Ante Markovic tried in the early 90s, but the break-up came to soon.
...an army coup in 1991. Landing with both feet on the Slovenian/Croatian secession, but also putting Milosevic on the sidelines. The Yugoslav's People's Army would have to disarm the regional forces and look for political solutions afterwards.
This is not unthinkable giving the basic initial loyality to the federation of its leadership and the high risk the territorial forces in Slovenia and Croatia were taking in their plans to resist.
...now this is ASB: a military intervention of either UN or EU forces with a preservation of a federal Yugoslavia on its agenda.
3. The situation today.
Compared to the Warsaw Pact nations, Yugoslavia as a whole was comparatively well-off, having access to the global market as a neutral power. Also, Croatia was on the way to become a major tourist destination, attracting more and more Western tourists.
The economies of all parts of it would have developed (partially extremly) better than in our timeline if the wars are avoided. Croatia reached the GDP of 1990 in 2003, Slovenia continued to grow in OTL, all other republic are still below 1990's numbers.
I found it hard to find comparable numbers; GDP per head in overall Yugoslavia was around 3500$ in 1990, this would have been higher than the CSSR (3100), Hungary (2800) and Poland (1700).
The latter states range between 9800 and 14400$/head today. I find it reasonable to assume that Yugoslavia would still enjoy at least a slight advance when compared to the Czech Republic (14400), while not reaching OTL's Slovenian figure of almost 21,000$.
For comparison: Portugal is at 18,950$, Greece/Spain/Italy between 29,500 and 33,500$.
An intact Yugoslavia would certainly have joined the EU in 2004. The Euro might have been introduced slightly later (as in OTL Slovenia), depending on their fiscal policies or they would still be on the soon-to-come list.
Also, bear in mind Europan funding of less developed countries. Infrastructure would be far better than in OTL, maybe not in Slovenia, but even in Croatia (if you wish to see a beautiful motorway, try the A1 from Karlovac to Split and beyond) - imagine a six-lane Autoput from the Austrian to the Greek border. Yugoslavia would be the transit country between the core of the EU and Greece/Turkey, as it had been prior to the wars.
After all, my resumee is: the Balkan wars of the 1990s was the case of a state and its populace stepping into a toilet and pulling hard on the flush!