I think 60% is a good guess. 65% tops IMO.
Obama got around 56% (if I remember correctly) so I think that's a good guess. If GOP runs social conservative, holy Lord it will be a slaughter. She'll get 65%.
Hillary is pretty damn well known and she has been weathering the political storm since about 1993. You might disagree with her policies (shes really not that liberal-more practical) but you would be hard pressed to find any candidate with similar intelligence, experience and political savvy. She's one bad MFer.