The network television season wraps up its final night of sweeps in fitting fashion, forcing viewers to choose between the season finale of television’s most popular showcase and its most compelling drama.

“American Idol” (7 p.m., Fox) ends its long process of elimination with a two-hour special. Perhaps the only real suspense here is how “Idol” will attract and keep viewers for the first 100 minutes or so, when everybody knows that the decision between Blake and Jordin will be announced during the last 10 minutes.

But if last year’s deliciously cheesy finale was any guide, there should be some odd moments to savor. And at least one of them will feature Sanjaya.

¢ “Lost” (8 p.m., ABC) also concludes with an extended two-hour helping. “Lost” seasons have ended with puzzling new developments that lead to a summer of head-scratching among the faithful. We’ve seen young Walt snatched by the Others, the discovery of the hatch, the explosion of the hatch and more seizures by the Others. Perhaps most baffling is that scene, far off the island, of snowbound-scientists certain that they had detected something. Huh?

Of course, the end of last week’s episode was every bit as good as a season finale. It’s not every day you see Charlie discover a bevy of Amazon gunslingers in the underwater outpost. But then again, the scene of Locke clutching a bullet wound in a pit of dead bodies has a certain season-finale ring about it as well.

When you come to think of it, a single episode of “Lost” can be more involving and mysterious than a whole season of some dramatic series. And that’s why it has emerged as one of the best dramas of this or any TV season.

¢ Neither history nor culture unfolds in neat, definable decades, but that doesn’t stop people from trying to describe them as such. “Saturday Night Live in the ’90s: Pop Culture Nation” (7 p.m., NBC) tries and fails to look at that decade as a coherent whole.

“The Blair Decade” (8 p.m., PBS, check local listings) does a better job, offering a profile of the departing British Prime Minister Tony Blair who leaves office on June 27, roughly ten years and a month after the landslide Labor party victory that brought him to power.

“Decade” looks at his handling of the death of Princess Diana (the subject of the Oscar-winning movie “The Queen), his personal stake in bringing peace to Northern Ireland and his partnership with two American presidents and Anglo-American military intervention in the Balkans and Iraq. The film is filled with interviews with heavy hitters from London and Washington, from Condoleeza Rice to Jack Straw.

Tonight’s other highlights

¢ Nancy Grace hosts “Snatched: Protecting Your Kids” (7 p.m., CNN Headline News).

¢ A witty, neurotic filmmaker uses vintage stock footage and personal interviews to explore his own insomnia and the nature of sleeplessness, a plague to millions in the documentary “Wide Awake” (7 p.m., HBO).

¢ Filmmaker Michael Apted revisits newlyweds he previously documented in 2002 in “Married in America 2” (8 p.m., Hallmark).

¢ Scheduled on “Dateline” (9 p.m., NBC): Angelina Jolie discusses her new movie “A Mighty Heart.”