Well, I do not know what you can achieve with V-ray but I guess displacement could work just fine if done correctly. With displacement, you can even use coplanar meshes without serious Z-fighting - one mesh could be textured with a wireframe pattern withOUT displacement while the other with the continents (and the rest transparent) WITH displacement (but this is only my theory - I have not tried).

Yes, displacement is something one should use sparsley as it is very slow. Though you might be able to adjust your settings and get acceptable result with smaller render times. But that will depend from model to model. If you want to create the geometry in SU you might want to try the Fur plugin: http://forums.sketchucation.com/viewtopic.php?t=28092

Could you post the model? or just one of the problem areas if the whole thing is too big. Theirs a chance theres some weird geometry making it go funny.