Just hopping in to toss out my own two cents on this debacle!
Personally, I feel that Russia should pressure (not arm) the separatists to lower their weapons and re-join the Ukraine, peacefully. They should then return the region of Crimea.
Once that is done, the US, Europe and Russia should pressure the Ukraine into allowing a referendum for all the regions which wish to depart, including Crimea, under threat of sanctions if they have to. This should all be done under observation by neutral international parties, not armed military guard.
Finally, I feel that the Ukraine (or what's left of it) should receive assistance in rebuilding from both the East and West for the unnecessary strain they were put through thanks to both sides.
Oh and I also want it to start raining lollipops and gumdrops every Tuesday, and for everyone in the world to gain super powers! And... and... unicorns are real! *mouth froth*
Silliness aside, I'm highly aware of the fat holes in such suggestions, with the biggest being that it requires enormous trust from some of the most paranoid governments in the world. There is also the question of Ukraine's sustainability without the oil rich region of Crimea.