After taking rather lengthy victory laps, both “That ’70s Show” and “Will & Grace” air their final episodes tonight.

The one-hour installment of “That ’70s Show” (7 p.m., Fox) also happens to be the sitcom’s 200th episode. Red and Kitty prepare to sell their house so they can move to Florida. The ever-cantankerous Red hardly throws out the welcome wagon for prospective buyers, so Kitty takes over. She then learns how difficult it can be to give house tours when every walk leads down memory lane. Cue the clips, please.

Meanwhile, the gang parties like it’s 1979. As they prepare to welcome the brave new world of the 1980s, Donna plans for college and Fez and Donna come clean about their mutual feelings.

¢ “Will & Grace” (7 p.m., NBC) says goodbye with a clip retrospective and interviews with cast and crew, followed by the finale (8 p.m.), in which the principles assess their lives in the wake of Grace’s blessed event.

This comedy has been around long enough to jump the shark any number of times. At its best, “Will” showcased clever, silly dialogue and made the most of the magical chemistry of its comic quartet. As the show progressed, these strengths took a back seat to increasingly petty and brittle dialogue and soap opera.

The story about Jack’s secret son gave way to the agonizing off-on-off story about Leo (Harry Connick Jr.) and the belabored artificial insemination interlude. As “Will” limps to the finish line, the story about Will and Grace’s shared parental duties returns, as sad and forced as ever.

¢ Three returning series wrap up their seasons with gunfire and cliffhangers. After a shooting, a team member clings to life on the season finale of “CSI” (8 p.m., CBS). Bullets fly as wounded prison inmates force their way into the hospital on “ER” (9 p.m., NBC). And a suspect opens fire on the FBI’s office on “Without a Trace” (9 p.m., CBS).

Tonight’s other finales

¢ On two episodes of “American Inventor” (ABC), the finalists create a promotional spot (7 p.m.), America elects a winner (8 p.m.).

¢ Graduation day arrives on “The O.C.” (8 p.m., Fox).

Tonight’s other highlights

¢ A New Yorker (Nick Cannon) joins a southern college marching band in the 2002 drama “Drumline” (7 p.m., WB).

¢ Kirsten Dunst and Cary Elwes star in “The Cat’s Meow” (6 p.m., IFC), director Peter Bogdanovich’s period piece about a murder mystery aboard a yacht party hosted by William Randolph Hearst and attended by Charlie Chaplin and Marion Davies. Based on real events. Or at least real rumors.