What would Sunday morning be like without Meet the Press? No one under 30 knows, because the Emmy-award-winning news show has graded the airwaves since 1947. This Sunday marks the 30th anniversary of television's longest-running series. For the occasion, the show will expand to an hour and Vice President Walter F. Mondale will "meet the press." Seven vice presidents have appeared on the show over the years, but none has enjoyed as much influence in the policy-making process of his administration as Mondale appears to have. Many White House observers consider Mondale one of President Carter's closest advisers. The interview will air Sunday at 11:30 a.m. on Channel 4.

If you're looking for something to watch tonight, the selection is much better than usual. Channel 2, the PBS station, offers Part 2 of an interesting dramatic series set in the 1880s. The show, entitled Best of Families, will appear regularly for several weeks, tracing the startling transformations wrought upon American society between 1880 and the turn of the century. Everyone in History 1621 should tune in, 9 p.m. on Channel 2.

For the lechers in the audience, Channel 5 presents Playboy's Playmate Party at 1:10 a.m. tonight. The 1977 Playmate of the Year will be crowned. Despite the appalling, bourgeois sexism of Hugh Hefner et al., the show must be better than its competition, the Tomorrow Show with Tom Snyder. Nevertheless, if you watch the Playboy fete, remember one thing: you can't claim you're only watching because of the well-written articles.

Comic book fans should check out CBS's movie version of The Incredible Hulk, Channel 7, 8 p.m., Friday. Bill Bixby plays the weakling scientist who transforms himself into a repulsively ugly creature with superhuman strength by exposing himself to massive amounts of radiation (gamma rays, for all those trivia nuts out there). Aficionados beware: television adaptations of superheroes have a notoriously poor track record. The book is usually much better.

The post-prime time scene this Friday features a few gems. The classic Western comedy Cat Ballou airs on Ch. 8 at 11:30 p.m. Unfortunately, Channel 8 is in New Haven and you may not be able to pick it up on your tv set, but if you've never seen this film and have nothing better to do, drive down there and stick around a week until the Yale game. This truly excellent film highlights the formidable talents of Lee Marvin, who received an Oscar for his performance as an alcoholic gunslinger.

If your car is not working, stay in Boston and tune in the Midnight Special (Ch. 4, 1:00 a.m.). Among the musicians appearing are Lou Rawis, Rod Stewart, Harry Nilsson, and K.C. and the Sunshine Band.

For the fighters, ABC will beam a heavyweight bout between Ken Norton and Jimmy Young, two leading contenders for the crown, live from Las Vegas on Saturday night, at 9 p.m. The winner stands a good chance of getting a shot at the current titleholder, and if you do not know who that is, you probably would not be interested in watching the fight anyway.

So, the television scene is looking up finally. Or maybe it's only my imagination.