THE PLT WAS FLYING HIS WIFE & HER 4 FRIENDS TO ASPEN, CO FOR A SKI VACATION. WITNESSES REPORTED THAT DURING TAKEOFF, THE RGT BAGGAGE DOOR OPENED. THEY OBSERVED THE ACFT TURN LEFT ONTO A DOWNWIND WITH THE LANDING GEAR EXTENDED. EIGHT WITNESSES REPORTED THE ENG(S) WERE PRODUCING POWER OF VARYING DEGREES; 2 STATED THE LEFT ENG STOPPED RUNNING & 2 REPORTED THE RGT ENG HAD A REDUCTION OF POWER OR RPM. IN THE VICINITY OF WHERE THE PLT WOULD HAVE MADE A BASE TURN, THE ACFT ENTERED A LEFT DESCENDING TURN, COLLIDED WITH THE TOPS OF TREES BESIDE A ROAD, IMPACTED IN THE ROADWAY ON AN EASTERLY HEADING, SLID TO A STOP & BURNED. AN EXAM REVEALED THE GEAR WAS DOWN, THE LEFT PROP WAS FEATHERED & THERE WAS EVIDENCE THE RGT BAGGAGE DOOR WAS OPEN. THE THROTTLE QUADRANT WAS FOUND WITH THE LEFT THROTTLE 2/3 FORWARD, THE RGT THROTTLE FULL AFT, THE LEFT PROP CONTROL IN THE FEATHER POSITION, THE RGT PROP CONTROL FULL FORWARD & THE MIXTURES AT ORNEAR THEIR FORWARD POSITIONS. THE FLT CHARACTERISTICS OF THE ACFT WERE CONSIDERED NORMAL WITH THE BAGGAGE DOOR OPEN.