Sure, “The Big Bang Theory” is often hilarious with its brainiac dialogue and geek appeal.

And “The New Adventures of Old Christine” continues to be underappreciated for being a sitcom about ordinary things heightened by the broad comedy of Julia Louis-Dreyfus and Wanda Sykes.

But the fall TV season hasn’t really started until tonight, when the brilliant “30 Rock” returns to NBC at 9:30.

It’s a shame, really, that the multiple-Emmy-winning-yet-still-ratings-starved show couldn’t better capitalize on Tina Fey’s Sarah Palin buzz earlier this month (instead, we got the unwatchable “Kath and Kim”), or even bask in some post-Emmy glow in September.

The waiting really has been the hardest part – but maybe “30 Rock” ’s late start will somehow benefit from Fey’s ubiquity.

Season three picks up with Jack Donaghy’s return to the hallowed New York building after a short stint working for the government in D.C.

Alec Baldwin is such a perfect network exec with his barrel chest and piercing stare. But his blustery exterior can always be punctured by Fey’s Liz Lemon, who greets him on the sidewalk in front of Rockefeller Center with the enthusiasm of a little girl opening her Barbie boxes on Christmas morning.

In Jack’s absence, the oily Devin Banks (the wonderfully melodramatic Will Arnett) has been running the company, much to the dismay of the staff.

Can you believe, Liz gripes to Jack, that Devin doesn’t know when to have the cake for the employees’ whose birthdays fall on the weekend?

Of course it’s done on Fridays AT LUNCH, Jack responds, shocked (!) at his nemesis’ ignorance.

But even though Jack is back, he’s not exactly in command, and watching him weasel his way back to the big office with the bay windows is a little wince-worthy.

Liz, meanwhile, has carried over her season two brainstorm of adopting a child and is tortured by the overbearing adoption agency evaluator – Megan Mullally, one of about 83 guest stars slated to appear this season.

Though the storyline is predictable – Mullally’s stuffy character takes issue with everything in Liz’s kinda-childproofed apartment and during a visit to Liz at work, the motley staff of “The Girlie Show” inadvertently creates all sorts of embarrassments – it’s the follow-through that demonstrates why “30 Rock” is the smartest show on TV.

Ardent fans might be disappointed that the goal of Thursday’s return is to catch us up and play out the loose ends of season two.

But make sure to set the TiVo season pass, because next week’s episode marks the show’s true homecoming.

Yes, it’s the one with Oprah – and let’s just say that a sleeping-pill-stuffed Liz getting counseled by the Divine Miss O on an airplane really is as bizarrely funny as it sounds and has a humdinger of a kicker – but it also demonstrates “30 Rock” ’s signature intelligence.

Jokes about the president’s approval rating, the Beijing Olympics and even Madonna’s freakishly sculptured arms are not only topical, but straddle the line carefully enough to appeal to people who read Entertainment Weekly or The Economist.

And even though we’d usually like to forget Tracy Morgan has a major role on the show as Tracy Jordan, the whack job star of “The Girlie Show,” his ongoing lawsuit with Jenna (Jane Krakowski, whose wide-eyed, hushed delivery should earn her an Emmy nod, too) over the pornographic video game he created last season is at least a useful subplot for his annoyingly manic character.

But it’s Liz who has our sympathy and admiration in this one, as Fey portrays her not with the exaggerated strokes of her other current character, but as a real person with a crooked grin, a wardrobe of jeans and tailored shirts and a totally relatable weakness for really bad junk food.