Sadly, whoever is acceptable to the Israelis is automatically disqualified by the Palestinians. The converse is also true; think about Israel's objections to Goldstone's Report on the Gaza war. The last problem with your premise is enforcement. Even if the UN reaches its own conclusions and decides to implement them, how can the enforce their will on the Israel and/or the Palestinians both Fatah and Hamas. If it comes down to "international sanctions" remember how long it's taken to do anything against Assad while he's killing his own citizens.
Syrian rebels call for regional alliance against Russia and Iran (Reuters)
from the article: Palestinian official: Mideast Quartet envoy Tony Blair 'useless'