Well, it's not really an RPG, but it has been reviewed here ;-) Some of the themes for King's Bounty:The Legend - well, one in particular: Under the shadow of an Oak
(http://www.youtube.com/watch?v=_jyDFm_FTws) - it was the combination of music withe the tranquil elven forest…I found myself going back to that area just to listen to it! (and look at the pretty sparkly unicorns…oooo pretty!)
Others: Morrowind intro was beautiful, and Icewind Dale/BG etc - agree with many of the other choices above.