BABY BOOM - When a little girl drops unexpectedly into her life, an ambitious businesswoman tries to combine child-raising and careerism. But her values soon tilt toward the family end of the scale, to the consternation of her executive cronies. The movie's portrait of yuppie life is wickedly hilarious, and Diane Keaton gives her funniest, most intelligent, most lovable performance in years. The screenplay loses its energy when our heroine moves from Manhattan to Vermont, though, and the filmmakers have an annoying habit of showing most non-New Yorkers as hayseeds and weirdos. Directed by Charles Shyer. (Rated PG) BEST SELLER - A book-writing cop agrees to chronicle the career of a strange man who claims he committed many murders in the service of a powerful businessman. Brian Dennehy and James Woods make a strong team as the skeptical author and the ingratiating lunatic, but director John Flynn diverts attention from their performances with nasty bursts of violence. The picture was written by Larry Cohen, still on the warpath against corporate skulduggery and establishment values. (Rated R) THE BIG TOWN - Seeking his fortune in Chicago, a young gambler falls for two women, an unmarried mother with a good heart and a stripper with a chip on her shoulder. The 1950s atmosphere is vivid and the cast is solid, except Diane Lane, who saves most of her energy for the unnecessary sex scenes. The story builds a good deal of momentum and then falls completely apart in the last 20 minutes or so. Directed by Ben Bolt. (Rated R) DOGS IN SPACE - The exploits of various punks, runaways, and backward-looking hippies who share a house in a run-down Melbourne neighborhood. Sex, drugs, delirious camera work, and a great deal of noise are the foundations of this aggressively bizarre Australian production. Richard Lowenstein directed. (Not rated) HAIL! HAIL! ROCK'N'ROLL - A portrait of rock-music pioneer Chuck Berry, with concert scenes featuring a band organized by Rolling Stones guitarist Keith Richards. Berry talks at length about his life and career, although he won't discuss some issues, including time he spent in prison years ago. Other people interviewed, such as rock stars Bo Diddley and Little Richard, offer valuable insights into the roots of Berry's style and the early rock scene as a whole. Taylor Hackford, best known as a fiction filmmaker, directed the overlong but marvelously energetic picture. (Rated PG) HELLRAISER - A ghoul seduces a woman in this particularly intense, particularly disgusting shocker. Written and directed by Clive Barker. (Rated R) SOMEONE TO WATCH OVER ME - While guarding a wealthy woman who witnessed a vicious crime, a married policeman falls in love with her. Although the picture is well acted and directed with Ridley Scott's usual meticulous attention to detail, Howard Franklin's screenplay is superficial and often trite. The violence is pretty rough, too. (Rated R) RATINGS: Films with ratings other than G may contain varying degrees of vulgar language, nudity, sex, and violence.