Television long ago replaced the fireplace as a family gathering point. Last night Americans could sit around their TV sets and end their Thanksgivings cozying up to the president of the United States as ABC presented "Ronald Reagan, at Home on the Ranch," starring Barbara Walters as herself.

The hour was an uncritical but engrossing encounter with Reagan that revealed, through his words or those of others, vulnerabilities never articulated quite so directly before. What viewers saw was a smart and good man rather than a brilliant and great one, a performer whose ingratiating personal style is getting its ultimate test as he faces grim political realities in Washington and the haunting aftermath of an assassination attempt.

The cumulative effect of this hour with Reagan and his family and friends was both cheering and troubling -- much as Reagan's daughter Patti said she found something "beautiful and frightening" in her father's eyes since the attempt on his life last March. One got the impression that no matter what his political fortunes may be over the next few years, Reagan seems unlikely now to want or seek a second term.

Perhaps what we ought to do every four years is elect one president and one national Nice Guy. Reagan seems ideally suited for the Nice Guy role, if intellectually underqualified for the presidency.

The first half-hour of the program, which included more generous views of Reagan's ranch than have been seen previously on TV, was basically so buttery that, should Reagan run again, the Republicans could use it as a rabble-rouser at their next convention. Reagan chops wood. Reagan feeds a carrot to his horse. Nancy and Ronnie's initials are carved in a stone. And Reagan goes for a jeep ride with passenger Walters, who bitches that this is "the scrungiest jeep" she'd ever seen.

Warm, folksy, western, rosy, cuddly, cute.

But there were also such telling moments as son Ron, usually camera shy, recalling the "strangely American nightmare" of keeping an assassination watch in front of a TV set, with his own father as a victim; and Patti, who called her father a "soft touch" (a phrase Reagan later used to describe himself) and noted the change in his demeanor since confronted so brutally with the specter of his own mortality.

"I really think he makes a better friend than a father," said Ron. And Reagan's brother Neal recalled how Ronnie used to fondle people's ear lobes as he talked to them. Again we saw him in film clips from another life, asking Pat O'Brien to "win just one for the Gipper" and, as a double amputee in "Kings Row" asking, "Where's the rest of me?"

There seems to be the makings of a great movie in all of this -- maybe the best American movie since "Citizen Kane." The script is being written and the scenes shot right in front of everybody's eyes.

During the interview segment, taped Wednesday, outdoors at Reagan's ranch, the president told Walters he did not fire his chatterbox budget director because "I think David Stockman was not the sinner, he was sinned against" by the reporter who quoted him. "Dave Stockman believes in our program," Reagan said. "You sure?" asked Walters. "Yes, yes," said Reagan.

He was not nearly as forceful in defense of embattled national security adviser Richard Allen. Reagan said the Japanese involved in the Allen scandal had corroborated damaging evidence against him.

His toughest decision? The veto of the federal spending measure earlier this week. His biggest disappointment? An inability to control leaks from his administration to the press. Reagan sounded almost like Jimmy Carter -- though sorrowful, rather than petulant -- when he sighed, "I've never known any place like Washington" when it comes to the contagiousness of rumors.

Walters stumbled over the line that separates inquiry from meddling when she twice asked the president about his nightmares. He told her he did not have "nightmares" but, touchingly, he did say the assassination attempt had shocked him into the realization that he could be a danger to those who travel with him when he ventures out in public.

ABC seemed to overload the first half-hour of the program with commercials so that the interview portion, about 20 minutes, could run uninterrupted. Still, commercials there were. Right after Reagan stood on a mountaintop and said, "God really did shed his grace on America, as the song says," ABC cut directly to a shot of Lola Falana shaking her flora and fauna for Chevrolet.

Later, after Walters had asked Reagan her stock momentous questions about doomsday planes and nuclear war, there was an ad for Atari video games in which a little boy gripped his throttle and shouted, "My mission in life is to save all of mankind!"

The hour, produced by Joann Goldberg "with the cooperation," according to closing credits, "of ABC News," was worth doing and worth seeing. Walters seemed to restrain her Mary Worth instincts and didn't ask the president to be good with us or gentle with us or anything else with us. But one would hope that no reporter would ever get more "personal" with a president still in office than Walters got last night. It just wouldn't be nice.