And this year's ceremony, televised live Sunday by CBS (8-11 p.m. EDT; 0000-0300 GMT Monday) from Radio City Music Hall, is packed with enough entertainment to keep its host very busy indeed.
Star performances will be abundant: from Elton John and the cast of "Billy Elliot" to Dolly Parton and the folks from "9 to 5." Eclectic, too: from Liza Minnelli to the 1980s hair-metal band Poison celebrating with the cast of "Rock of Ages." Plus, of course, scenes from the nominated best musicals and best musical revivals.
And we haven't even gotten to the list of celebrity presenters that will include such names as Nicole Kidman, Anne Hathaway, David Hyde Pierce, Jessica Lange, Frank Langella and Kevin Spacey. When will there be time for thank-you speeches?
"I certainly never thought this would be in the cards," Harris says of his Sunday gig. "All of a sudden it came into my world, and I was ecstatic. It's the biggest night on Broadway and to be able to helm the ship is amazing. I get an all-access pass. It will be the best seat in the house."
Harris comes to the Tony job with some experience. He had good notices hosting the 2009 TV Land Awards in April and he's done similar work for the Writers Guild, various magic organizations (Harris is a magic buff) and the Ovation Awards, Los Angeles' theater prizes.
BT McNicholl, who put Harris into the Roundabout Theatre Company revival of "Cabaret" in 2003, says Harris' interest in magic will help the actor with his Tony duties.
"Neil is a first-rate magician," says McNicholl, associate director of "Cabaret."
"And I think the timing and concentration that are required of people who successfully practice sleight of hand has served him well in the theater. He knows how to keep an audience's attention and focus it in all the right ways. Plus Neil has a very warm and appealing presence, not to mention a sense of comic timing that goes back to the greats of yesteryear. It's in his bones."
For those who only know the 35-year-old Harris as the womanizing Barney Stinson on his current CBS sitcom or from his breakout TV role as "Doogie Howser, M.D.," the actor's theater career may come as a surprise.
"I suppose the Tonys will show them that I am knowledgeable in the theater." Harris says. "But I am not out to show anyone that I am theater-worthy. Quite frankly, I am happy if the people who are watching in middle America think that I am the guy from 'How I Met Your Mother.' But what I am passionate about, in person, is theater."
"Les Miserables" was the first musical Harris ever heard - years ago - on a cassette tape.
"I was going to a theater camp at New Mexico State University," says the Albuquerque-born Harris. "It sounded very operatic, and I didn't quite get it. Then, later, on my first trip to New York, ('Les Miz') was the first show that I saw. ... And to see the show's barricade come rumbling on stage and the turntable spin around - plus the giant flag waving in the background. It was a jaw-dropping moment."
The actor made his Broadway debut in 2002 when director Daniel Sullivan put a replacement cast into the Pulitzer Prize-winning "Proof," a new ensemble that not only included Harris, but Anne Heche, Len Cariou and Kate Jennings Grant. From there, Harris went into "Cabaret," as its androgynous, flamboyant master of ceremonies.
"That's the beauty of theater," he says. "From role to role, you really get to embody an entirely different world - 'Proof' being super-cerebral and then getting to follow that up with a stint in what is almost like a Cirque du Soleil show."
Harris has been steeped in the work of Stephen Sondheim, too: a pair of concert versions of "Sweeney Todd" - one in Los Angeles, the other New York - in which he played the murderous Todd's young assistant Tobias.
Then there was a return visit to Roundabout's Studio 54 where in 2004 he appeared as the Balladeer and John Wilkes Booth in a revival of "Assassins," plus a recording of Sondheim's TV musical, "Evening Primrose." And he became an Internet musical-comedy sensation in the Web entertainment "Dr. Horrible's Sing-Along Blog," playing the title character created by good friend Joss Whedon.
Because "How I Met Your Mother" occupies his time for seven months a year, there is little time for Harris to do stage work. That's why he is grateful for the Tony job and modest about his contribution to the show.
"We really want to make sure that people who watch the show get a good sense of what's there on Broadway," he says. "To spend too much time watching the host dance around and sing a song takes away time from the shows that deserve that (attention)."
Yet the actor is ready to improvise and deal with the unexpected, and McNicholl is confident Harris can pull it off.
"When he was doing 'Cabaret,' his scene partner was the audience," McNicholl says. "And his ability to simultaneously hear them, bounce off them and drive the show was a joy to watch. So he's been an emcee on Broadway before. I don't see why Sunday night should be any different."
By Michael Kuchwara