Two resplendent acting ensembles contribute to an exemplary evening of family entertainment on the CBS Television Network tonight. First there are those irresistible lackeys of the media-industrial establishment, The Muppets, in "The Muppets Go Hollywood," at 8 on Channel 9, and then an ultra-stellar cast in a new production of Kaufman and Hart's "You Can't Take It With You" at 9.

When "The Muppets Go Hollywood," Hollywood goes Muppets, and vice versa. Although the hour is essentially an extended plug for the upcoming "Muppet Movie," to be released this summer, the program is filled with the sort of cheerful chicanery which has made the globally syndicated "Muppet Show" one of the most popular TV programs in the world.

Even if it were the only highlight, and it isn't the hour would be worthwhile just for the sight of the very redoubtable Miss Piggy lounging poolside in her heart-shaped pink sunglasses and dictating letters to a secretary."Let's just end this by saying, 'We must have lunch some time. . .Best to Rosalynn and Amy. . .kissy-kissy, et cetera," she recites.

Most of the hour was taped at a big Hollywood party that was thrown to provide a focal event for the special. Ho-hum interviews with celebrities who attended are unnecessary but brief, and there are such semi-precious sights as Chris "Superman" Reeve disco-dancing with the Divine Miss P., or Kermit the Frog arriving in an old woodie station wagon. "Animal" runs through the crowd like Harpo Marx, nipping at Cheryl Ladd or any other pretty girl within tooth's reach, and Fozzie is humiliated at the Chinese Theater when he is mistaken for another illustrious bear, Smokey The.

To some extent, the program suffers from Muppetus Interruptus. Paul Williams, who has always suggested a Muppet that didn't quite turn out right, brings the hour to a yawning halt with a song he wrote for the film. Cohosts Dick Van Dyke and Rita Moreno tend to be just a pair of grins in the way. But then, who can upstage a Muppet? Miss Piggy makes mincemeat of Raquel Welch and Kermit's amphibious magnetism out-charms Superman by a mile.

The program, directed by Stan Harris and produced by Muppet creator Jim Henson, has ragged junctures and split seams, but The Muppets still romp supreme. "Kermit, are we really stars?" Gonzo asks near the show's end."Well," says Kermit, "close enough." May The Muppets go forth and multiply.

If The Muppets are the folklore of the '70s, "You Can't Take It With You," written by George S. Kaufman and Moss Hart in 1936, has a peace of its own in permanent American mythology. It ranks among the most beguiling comic statements ever made in a theater on behalf of eccentricity, individualism and isolationism.

Paul Bogart, who has directed many episodes of "All in the Family," and who is always just this side or just that side of brilliant, adapted and directed this new TV version with high fidelity to the original script and a warming sense of romanticism. He didn't go for two hours chock full of yocks but rather for an infectiously sweet and pleasing interpretation.

And what a cast.Even a tiny role like Mr. Henderson, the simpering IRS man, is played by a heavyweight-Howard Hesseman, "Johnny Fever" of the sit-com "WKRP" in Cincinnati." There are several series TV actors in the show, but that does not mean Bogart has reduced the play to sit-comterms. He has toned it down but spruced it up at the same time.

The play takes place in the Sycamore household, where havoc is the order of the day and where the term "living room," according to the original stage directions, "is something of an understatement." Dear Penelope (Jean Stapleton) is writing plays about monasteries and brothels, old Grandpa (Art Carney) collects snakes and attends commencement exercises, daft daughter Essie (Beth Howland, of "Alice") takes dance lessons from the mad Russian Kolenkhov (Kenneth Mars) and, down in the cellar, Penelope's husband Paul (Eugene Roche) and former ice man Mr. De Pinna (Harry Morgan) are cooking up a riot of fireworks.

All these actors are wonderful to varying extremes in their roles, but the production is really given a solid center by the two romantic leads, Blythe Danner as the outwardly sanest member of the family and Barry Bostwick as the rich kid from a proper home whom she wants to marry.

Danner, so convincing and provocative in "Too Far to Go," the NBC movie adapted from John Updike stories and shown earlier this season, proves just as adept at light comedy; she seems always to enter on a breeze, and an invigorating one at that. Bostwick, who lit up the parody "Movie Movie" on the big screen last year, makes an ideal partner for her. Together they are intoxicatingly fresh and chipper.

Bogart did a beautiful job of maintaining period authenticity without going into a nostalgic tailspin. There is, thank heaven, no laugh track, but the action is cushioned with a delicate and appealing musical score by Arthur B. Rubinstein. Everyone involved has seen to it that "You Can't Take It With You" returns in captivating style. CAPTION: Picture, Miss Piggy at poolside in "The Muppets Go Hollywood"