AN OPEN LETTER TO DAVID LETTERMAN:Dear Dave, You certainly must be relieved to put this whole Los Angeles-New York question behind you, if only to prevent more badly written top 10 lists by local politicians. That was the easy part. After all, who really wanted to tempt the fates by doing a late-night talkshow in studio space haunted by the spirit of “The Pat Sajak Show”? Thanks, but we’ll buy a vowel or solve the puzzle. The hard part will be introducing the new show with the media watching your every move, though the level of interest between L.A. and New York (except perhaps the folks back home in Indiana) remains highly suspect. Even with the venue settled, you should have only a brief respite from media scrutiny. The press will be so eager to get info they may try anything short of breaking into your house. (By the way, that woman they kept finding in your living room doesn’t work for the New York Post, does she?) At any rate, the purpose of this missive is merely to offer some friendly advice — now that the “where” and “when” of the move have been addressed — about the broader, longer-term implications of shifting from NBC to CBS. In no particular order: n While it’s understandable that you coveted “The Tonight Show” time period after all those years behind Johnny, the worst thing you could do now would be to change your show to somehow try and make your comedy more palatable to an earlier audience. If it’s funny at 12:30, it’ll be funny at 11:30. … assuming anyone in the usual CBS demographic can stay up that late. n Remember that curiosity will likely provide high ratings initially, but it will quickly subside, so don’t panic. It’ll take several months before you find your true level, just as it did with Jay Leno. n CBS executives are weasels, too. They know it. Heck, they want to be publicly ridiculed. How else can you explain how vigorously they pursued you? So go ahead, lampoon and harpoon them, just as you have NBC and General Electric over the years. Admittedly, taking potshots at the boss loses something when that boss is paying you somewhere north of $ 40 million over three years, but a talkshow host’s gotta do what a host’s gotta do. n No matter how much CBS urges and prods you, don’t get carried away with interviews touting the launch of the new series. Why fuel the media’s expectations and your own overexposure? Let’s face it — snottiness is a big part of your charm. Give a quote to Entertainment Weekly, make an appearance at the TV Critics Tour in July, but leave the long-winded GQ and Vanity Fair profiles to someone else. n More Connie Chung, less Jane Pauley. … unless you have to apologize for something. n Tom Brokaw makes a fine guest, as anchors plugging the network go, but beware of Dan Rather, the original loose cannon. He likes to indulge in really awful homilies understood only by guys named Bubba. Resist putting him on at all , unless the show’s ratings are in the toilet in Texas. n Avoid taking too many extended visits to tape the show in Los Angeles. A couple of weeks during February or May might be fun once a year, but try and keep it special. Besides, living out here rots your brain, cabs don’t come around unless you call for them, and most business is conducted on a drive-through basis. Fotomat booths are hardly the setting for “May We See Your Photos, Please?” Nerves are also a bit jangled in L.A. these days, and a lot of people are heavily armed, which should make camera crews a little antsy about those on-the-street interviews. Even then, where would you do something like that adjacent to Television City? Interrupting diners at health food restaurants along Beverly Boulevard or harassing old folks at the Farmer’s Market doesn’t have the same allure as passersby at 30 Rock. That’s all for now, except to say congrats on the new space and, belatedly, the new gig. If you don’t get carried away, as Ed Sullivan would say, it should be a really big show. P.S. As I write this, I’m not wearing pants. NEWS, NEWS, NEWS: With the arrival of ABC and CBS newsmagazines later this year — plus another NBC hour, assuming they can wipe away the “Dateline” flap stigma — the three networks will provide an unprecedented 10 hours of news division programming, at a minimum, by this summer. That’s not to mention a planned magazine (“The Acne Update,” perhaps?) from Fox News. That’s hardly good news for those who make their livings off dramas and sitcoms. It bites into the precious 80 hours currently programmed by the three networks and Fox in prime time, already curtailed by six movie slots and multiple reality series. Aside from the repercussions of a news overdose, which may have contributed to the “Dateline” gaffe, CBS Entertainment exec VP of prime time Peter Tortorici raised an interesting point last week. He noted that newsmagazines don’t have to face like-themed competition in the same time period — unlike comedies or dramas, where (with the addition of Fox) two and sometimes three like-formatted shows routinely duke it out. Tortorici rightly pointed out that news has thus far been used as counterprogramming and that the audience will be diffused a bit once such shows have to square off in the same time period, which is inevitable. There were even rumors a while back, subsequently denied, that CBS might try an all-reality night Thursday, possibly pitting a news shows against ABC’s “PrimeTime Live” once “Knots Landing” has alit for the final time. ABC did consider putting its new Forrest Sawyer-fronted newshour opposite “60 Minutes,” and it still seems possible that a network — particularly ABC, which has enjoyed its greatest success lately at 10 p.m., thanks to its news division — could strip news five days a week in that hour. Tortorici observed that the audience for news is “fairly inexhaustible” and a single show could probably be supported in every hour of prime time. After the “Dateline” affair, however, one has to wonder whether there’s enough good news — or even bad news — to go around.