WORTH NOTING ON TV

* THURSDAY

Knots Landing: a `Block Party' and a Last Edition (CBS, 8-11 p.m.): Several long-running series - like this show, "Cheers," "Quantum Leap," and "The Wonder Years" - are bowing out this season in an orgy of expanded editions and fond reminiscences. "Knots Landing," a steamy, soap-opera-ish program not universally admired despite its popularity, premiered in 1979, putting it near the top of the longevity list. The final episode will be preceded by "Block Party," in which its stars recall favorite episodes with the help of old clips, an approach that's becoming a common endgame for these marathon series. The practice milks the reservoir of memories and loyalty on the part of long-term fans, and it capitalizes on the occasion to create an "event" program of the kind that has done increasingly well in ratings during the past few years. In the final show itself, actor Donna Mills returns, joining Ted Shackelford and Michele Lee, who have been cast members since 1979. * FRIDAY

George Marshall and the American Century (PBS, 9-10:30 p.m.): This in-depth documentary profiles a great man often overshadowed by the military stars of World War II - like Douglas MacArthur and Dwight D. Eisenhower - despite his enormous contributions. These include his military master-minding as chief of staff, his service as Secretary of State, and his sustaining achievement, the Marshall Plan, that helped postwar Europe recover and won him the 1953 Nobel Peace Prize.

USS Wisconsin: The Last Battleship (PBS, 10:30-11 p.m.): As subjects of a documentary, these ships are a natural - especially this battleship, the last to be built in the United States. It saw duty from World War II right up through the Persian Gulf war, and its 16-inch guns - you'll see and hear them fired for the last time - are the largest operational ones in any navy. The show's producer and a reunion crew of some 200 former sailors from the ship took a cruise that yielded interviews and other bits o f nostalgia and history.

Please check local listings for all programs, especially those on PBS.