AN ACR CREW LINED UP ON WRONG RWY DURING A MULTIPLE RWY OP PARALLEL RWYS.

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WE WERE ON RADAR VECTORS FOR THE ILS RWY 35R AT DEN. TSTMS WERE TO THE SE AND APCH WAS TURNING ACFT TO AVOID THEM. WE WERE IN IMC DURING VECTORS. ARRIVING FROM THE E; WE WERE GIVEN A R TURN TO A HDG TO INTERCEPT THE LOC AND CHANGE TO TWR FREQ. WE INTERCEPTED THE LOC JUST AS THE TWR WAS COMING ON AND IMMEDIATELY SAID 'ARE YOU CORRECTING BACK TO THE R?' WE REPLIED IN THE AFFIRMATIVE EVEN THOUGH WE WERE ONLY INDICATING FRACTIONALLY L OF COURSE. IN CORRECTING; WE WENT R OF THE LOC AND GOT BACK ON LOC AT ABOUT THE MARKER. AT THIS POINT WE ACQUIRED THE RWY AND PROCEEDING TFC VISUALLY; WHICH WE ADVISED THE TWR. THEY THEN ADVISED US THAT WE WERE ALIGNED WITH THE WRONG RWY; RWY 35L. A GAR WAS FOLLOWED BY A NORMAL APCH AND LNDG. NO TCASII ALERTS OR KNOWN LOSS OF SEPARATION OCCURRED. CHAIN OF EVENTS: THE APCH BRIEF WAS THOROUGH AND STRICTLY STANDARD OPERATING PROC. THE RWY IDENT IS MENTIONED; AS IS THE PLATE NUMBER; LOC FREQ; AND DECISION HT. IT IS BELIEVED THAT; AFTER THE BRIEF; THE FO PUT THE PLATE ASIDE THEN SUBSEQUENTLY CHOSE THE WRONG PLATE PRIOR TO TUNING THE RADIO. (WE HAD LANDED ON RWY 35L EARLIER THAT DAY.) I DID NOT VERIFY THE FREQ AFTER TUNING (NOT STRICTLY REQUIRED; IN FACT; PF IS SUPPOSED TO CALL FOR RADIO TUNING WHEN HAND FLYING.) HUMAN FACTORS: FATIGUE. THE END OF A LONG DAY FOLLOWING AN EARLY MORNING START. FO ADMITTED GETTING ONLY 4 HRS SLEEP. (RETURN FROM VACATION XA30 PM; ASLEEP XC00; UP AT XG AM.) PERHAPS A FACTOR: SHE'S 4 MONTHS PREGNANT. SHE TOOK 'CTLED REST' ON THE FLT DECK AT LEAST TWICE. SHE SEEMED EXHAUSTED ALL DAY. IN RETROSPECT; I WISH I HAD ADVISED HER TO GET OFF THE TRIP IF SHE DIDN'T FEEL 100 PERCENT. I HAD BEEN AWARE OF HER BEING 'DISENGAGED' ALL DAY. SUPPLEMENTAL INFO FROM ACN 336669: THE GPWS WIND SHEAR INOP LIGHT ILLUMINATED. CAPT ASKED WHY WAS THAT ON; SO CHKED CIRCUIT BREAKERS AND LOOKED UP LIGHT IN TRAINING MANUAL.