WORTH NOTING ON TV

* WEDNESDAY

Doug (Nickelodeon, 5:30-6 p.m.): Nickelodeon offers younger viewers an alternative to traditional Thanksgiving programming with the ''Non-Stop Nicktoons Weekend.'' The marathon, which continues through Sunday, features animated programs that children selected during a letter-writing and phone-in campaign. Beginning with this episode of ''Doug,'' the weekend also includes ''Rugrats,'' ''AAAHH!!! Real Monsters,'' ''Rocko's Modern Life,'' and ''The Ren & Stimpy Show.''

The Soul Train 25th Anniversary Hall of Fame Special (CBS, 9-11 p.m.): Arsenio Hall hosts this tribute to the popular weekly dance program. Highlighting the special are performances by Al Green, M.C. Hammer, Michael Jackson, Patti LaBelle, Diana Ross, Bill Withers, and Stevie Wonder, who are inducted into the Soul Train Hall of Fame.

* THURSDAY

The 69th Annual Macy's Thanksgiving Day Parade (NBC, 9 a.m.-12 noon): Elaborate floats, marching bands, and giant helium balloons make their way along New York's Broadway in this traditional event. Katie Couric and Willard Scott of ''Today'' host the telecast, which includes performances by Jon Secada, All-4-One, and Rosemary Clooney.

Murder, She Wrote (CBS, 8-9 p.m.): The mystery series celebrates its 250th episode with Jessica (Angela Lansbury) piecing together a story of wrongdoing among international art thieves.

* FRIDAY

Free Willy (CBS, 8-10 p.m.): The film about a boy and the whale he befriends premieres on network television.

Across the River (PBS, 9-10 p.m.): Tough inner-city neighborhoods like Washington's Anacostia area are searching for solutions to many steep challenges. In this program, journalist Hedrick Smith explores some exemplary grass-roots projects that are turning Anacostia around - such as the Alliance of Concerned Men, who mentor at-risk youths.

Please check local listings for these programs.