@ Herzen's love-child & Hörnla:
Sounds fine but who would be the reasonable leadership? In Serbia the Democrats were, just like today, devoid of any energy, charisma or initiative so that you only had the choice between Milošević, Drašković and Šešelj. And most people who were against Sloba rallied behind Drašković.
My impression is that such a "reasonable leadership" in Serbia/Croatia doesn't necessarily need to consist of purely democratic/pacifistic angels. The proposal I edged out still entails a Greater Serbia and an independant and expanded Croatia. The victims would be the weakest fraction: Muslim Bosniaks, who, though, would after a peaceful separation of Croatia not be in a position to fight for their independance.
So Belgrade could declare that "our Serbs brothers in Croatia and Bosnia have been liberated and united with the homeland" while Zagred could point out that "while we lost some hilly backwaters whose inhabitants would only be a headache anyways we have won a desperately needed hinterland for the economically important Dalmatian Coast".
And I also understand that the escalation in Yugoslavia had a lot to do with a failure to understand the delicacy of the post-Communist transition of this country in the West (also in the FRG). We Germans transferred billions into the GDR and to Russia/the Soviet Union (actually to the USA as well during the Kuwait war).... being Santa Claus to Yugoslavia wouldn't have hurt us.
Croatia giving up Krajina is as likely as France giving up Marseille to Algeirs when french become a minority there. At the same time Croat held areas in Herzegovina amounts for less than a 1/3 of Croats in BiH.
The comparison you use is IMHO a bit imbalanced and rather suits the Kosovo, where the demographic trends shifted considerably during the latter half of the 20th century (in favour of the Albanians).
If I am not completely misinformed, we speak about traditionally Serb resp. Croat areas here.
I agree that giving up the whole area of the 1991-95 Serb Republic in Croatia (an entity with only a 52%-share of Serbian inhabitants) would have been unimaginable for Croats and geographically hardly feasible. How about such a line, though? (see below)
In 1991. BiH is not dividable along the ethnic lines without major population transfers or ethnic cleansing.
About BiH, maybe it isnt possible to divide her on ethnic lines ( at least so that you can satisfy all sides ), but you could transform her into federation of 3 nations, without territorial continuity, it is possible...
There is no perfect division there, neither in Croatia if you want to get Serbian majority-areas out. BUT the chances for such a new order to allow minorities to live as a diaspora are better if they are carved out before battles are fought, civilians murdered and thousands expelled. Remember, all the ethnicities speak variants of the same language and also do not differ racially. "Only" the religious, historical and cultural background differ.
Actually, these should be favourable circumstances, because IMHO, the worst divides would be language (for practical reasons) and race (for reason of visibility). If all Constitutions of the follow-up states include a definition of minority-rights (rights of passage, free speech, free use of language, free religious choice, quoroms in elections, mutual acceptance of school/professional/university-degrees), the majority of people belonging to a minorty should at least find it acceptable to live where they used to although the state is not the one they might dream of.
Of course, for everything we talk about here, a time-window which rapidly closes the more acts of violence occur, or perhaps once they do...
Though personally I think that the sole concept of Yugoslavia should have been put ad acta after World War II.
The way they were OTL, Yugoslavia was bound to fail, and it shouldn't have come into existence at all. Perhaps an expanded Serbia as a result of a WW1-compromise-peace would have been a better solution (with Croatia/Slovenia being part of a confederalized Danubia). I am not informed enough if a thoroughly federalized SHS-kingdom might have worked post-1918 or if the players back then wouldn't have acted against each other under all circumstances. Are there chances that a different Constitution in Tito-times would have worked better after his death? AFAIK, whoever calls for a "more federal" Yugoslavia doesn't see that post-1980-YU already was legally very federalized, even the armed forces (its Constitution included the right to secede! Imagine that in the US constitution!). To me it seems, that only the One-Party-System held it together. Once the Party dissolves or its dominance crumbles, nothing was left to bind the republics together.