FLC OF ACR LGT ACFT HAVE DIFFICULTY MAKING AND FOLLOWING A PUBLISHED VISUAL APCH RESULTING IN ATC ASSIGNING PARALLEL RWY TO THAT ORIGINALLY GIVEN.

Narrative

ATIS ADVISED ILS 16R IN USE AT SEA. APCH WAS SELECTED IN FMS AND BRIEFED. IN THE BASE TURN AT APPROX 6000 FT APCH ASKED IF WE HAD HUSKY STADIUM IN SIGHT. WHAT WE SAW WAS ACTUALLY THE KINGDOME; BUT WE ACKNOWLEDGED AND WERE CLRED FOR THE HUSKY VISUAL TO 16L. THERE IS NO SUCH APCH; THE HUSKY VISUAL IS TO 16R. IN THE CONFUSION OVER THE CORRECT GND TRACK TO FOLLOW; OTHER VISUAL TFC CLRED TO 16R HAD TO BE ADJUSTED FOR OUR FLT PATH. FORTUNATELY; THE OTHER ACFT HAD US IN SIGHT. TCASII IN OUR ACFT ADVISED A TA 'TFC.' NO EVASIVE ACTION WAS REQUIRED AND WE ULTIMATELY WERE CLRED TO LAND 16R AND THE OTHER ACFT LANDED 16L. MY SUGGESTIONS FOR CORRECTIVE ACTIONS WOULD BE TO REQUIRE ALL APCHS IN USE BE INCLUDED IN THE ATIS; ADVISE THE PLTS TO 'PLAN APCH TO' AS EARLY AS POSSIBLE; AND NOT CHANGE IT IN THE BASE TURN. I WILL NEVER AGAIN ACCEPT A CLRNC TO AN APCH I HAVEN'T BRIEFED. IN THE SAME CIRCUMSTANCE I WILL ONLY ACCEPT CLRNC FOR A VISUAL APCH TO RWY XX. DIGGING OUT THE (AERO) CHART AND READING IT TO PREPARE FOR APCH SHOULD NOT BE DONE ON BASE TO FINAL. ALSO; CTLRS SHOULD NOT MODIFY A PUBLISHED APCH.