THE PLT OBTAINED A WX BRIEFING FROM LAS VEGAS FSS AND WAS TOLD THAT FLT UNDER VFR WAS NOT RECOMMENDED FOR THE PROPOSED FLT TO DURANGO (DRO). THE PLT FILED A VFR FLT PLAN AND DEPARTED LAS VEGAS. OVER PAGE, AZ, HE FILED A PIREP AND WAS AGAIN TOLD VFR FLT NOT RECOMMENDED. N6105R LANDED AT BLANDING, UT (BDG) DUE TO SNOW AND THE PLT AND HIS PASSENGERS HAD THANKSGIVING DINNER WITH THE AIRPORT MANAGER. THE PLT THEN CALLED HIS WIFE IN DRO WHO SAID THE WX WAS OKAY, OBTAINED A WX BRIEFING FROM CEDAR CITY FSS, AND DEPARTED BDG. THE AIRCRAFT CRASHED APPROXIMATELY 2 MILES NNE OF THE CORTEZ AIRPORT, ABOUT HALFWAY BETWEEN ITS DEPARTURE POINT AND ITS DESTINATION. IT CAME TO REST IN A SNOW COVERED RAVINE ADJACENT TO A HIGHWAY. WITNESSES SAID VISIBILITY WAS RESTRICTED DUE TO SNOW, FOG, AND DIMINISHING DAYLIGHT. THE PILOT WAS NOT INSTRUMENT RATED. ANALYSIS OF THE PILOTS GASTROCNEMIUS MUSCLE TISSUE REVEALED 0.057% ETHANOL AND LESS THAN 0.005% TERT-BUTANOL, A FORM OF HEAVY ALCOHOL.