NEW YORK – Nearly two dozen guitars are scattered on the floor and sofa in Conan O’Brien’s office in Rockefeller Center, most of them gifts from musicians like Eddie Van Halen, Los Lobos, Les Paul and Brian Setzer.

Moving day approaches.

O’Brien is about to pack up the guitars – and himself – for the trip West, when he replaces Jay Leno as host of NBC’s “Tonight” show in June. First things first, though, as a nostalgic O’Brien prepares for the last week of his 16-year run at “Late Night.” Feb. 20 is his last show before turning it over to Jimmy Fallon.

He usually enters his office from the Sixth Avenue side, where Rockefeller Plaza is indistinguishable from any other New York office building. Lately, though, he has looped around to the Fifth Avenue side, walking past the skating rink into the far more impressive eastern entrance.

“For a while, I was in denial – ‘Oh, we’ll just stop doing this show and we’ll move on to the next one,'” he says. “That’s very me, very male. Men don’t like to say goodbye. My wife told me about six months ago: ‘I think you have to admit that you have mixed feelings about leaving this late-night show, it’s very emotionally charged for you. That’s OK.'”

He’s been sifting through show highlights from over the years, playing “greatest hits” clips during the last few weeks. Many are suggestions from viewers.

The other night he watched his very first show for the first time in years.

That was a pretty emotionally charged time, too. As an unknown chosen to replace David Letterman in 1993, he was brutally panned and nearly fired. Given the chance, he improved to the point where those bad days are a distant memory.

From the very beginning, he says, it was the show he wanted to do. Even recent Conan converts would recognize some of the humor from that first show: He’s depicted walking down a street where a talking horse calls out to him “Better be as good as Letterman.” He sang “Edelweiss” hand-in-hand with Tony Randall as the camera cut to a crying Nazi in the audience.

“I’m proud of the show’s originality,” he says. “Letterman’s ‘Late Night’ was obviously brilliant and groundbreaking and changed all of the rules and I’m very proud of the fact that our show, in its tone and its look and its approach had very little to do with the show that came before it or, I think, any other show that came before it.”

Unpredictability and a childlike silliness were its defining characteristics.

His “clutch cargo,” or fake interviews with pictures that had moving lips, also showed up during the very first week. He traveled to Finland to “take over” the country. He drove around Houston at 2:40 a.m. to see what was going on at that hour – the time his show was carried by the local NBC affiliate. At the late hour of his telecast – most NBC stations carried him at 12:35 a.m. – a surreal sketch in which O’Brien stripped his shirt to impersonate Led Zeppelin frontman Robert Plant, then morphed into a medieval sword fight with George Plimpton, made some kind of sense.

NBC had committed to giving him the “Tonight” slot five years ago, although it was only recently that current host Jay Leno decided to stay with the network and do a nightly 10 p.m. show.

Most of O’Brien’s writers will head to California with him. Years ago, switching to that earlier time slot might have meant dramatically changing the tone of the show to appeal to an older audience. But the late-night habits of viewers are different now – many watch the next day on digital video recorders – and the need for such changes has lessened.

“The shows are an extension of the host and, like it or not, this is my sense of humor,” O’Brien says. “It would be a mistake to reinvent myself as a completely different person now.”

His biggest danger moving to Los Angeles, outside of sunburn, is overthinking things. And O’Brien will be facing more formidable competition with Letterman. Although O’Brien generally maintained the top ratings position in his time slot, CBS’ Craig Ferguson has been catching up.

After Leno’s surprise announcement that he’s staying with NBC, there was immediate speculation that it might be bad for O’Brien, that he’d lose out on booking wars and still be seen as a second banana to Leno.

But O’Brien said one night on “Late Night” that he was looking forward to the new schedule.

“You can talk to me in a year and I’ll say ‘Well, there are some problems, there are some complications,'” he said. “But I don’t know what they are. I don’t know if there will be.”

Even as it became clearer that Leno wasn’t eager to leave, O’Brien didn’t waver in wanting to keep to the original deal. He never got a sense that NBC wanted to change, either.

O’Brien is trying to maintain the element of surprise for his last week of shows, saying he wants to rely on old friends of “Late Night” instead of stunt casting. Don’t be surprised if Andy Richter, O’Brien’s on-air sidekick until he left in 2000, stops by. Same with Al Roker who, because he works in the same building, has been the show’s most frequent guest.

“The one thing that’s worked consistently for me is just to use your common sense, just try to be funny,” O’Brien says. “For 16 years, I’ve just been trying to think of funny stuff. We miss sometimes, we hit sometimes but I think our average is pretty good.”