This guide is designed to alert readers to the scope and variety of programming coming up. Listing is not meant to represent blanket endorsement. Viewers are urged to be selective. SATURDAY Evening at Pops (PBS, 8-9 p.m.): The Smothers Brothers - Dick and Tom - do their comic capers, and conductor John Williams debuts his own ``Olympic Fanfares for Summer 1988'' SUNDAY National Audubon Society Special (PBS, 8-9 p.m.): ``Wood Stork, Barometer of the Everglades'' shows how this species can reveal man's meddling in Florida's vast ecological system. The Natural (NBC, 8:30-11:21 p.m.): Yes, it's a repeat. But many people who missed it will jump at the chance to see the well-loved Robert Redford film about an aging player who gets a chance.
MONDAY American Masters (PBS, 9-10 p.m.): ``Lillian Gish : The Actor's Life for Me'' - the season premi`ere of this series - profiles the ``first lady of the silent screen'' through clips and interviews with Miss Gish herself. Drugs: Why This Plague (ABC, 8-9 p.m.): Tough, graphic historical look at why so many Americans are involved with drugs - and how this problem might be solved.
TUESDAY The Struggles of Poland (PBS, 9-10 p.m.): Premi`ere of a nine-part series that offers one of Western TV's first-ever in-depth historical looks at Poland. This episode reviews the 1905 revolt after the Russo-Japanese War and other key events leading to Poland's conflict with the Soviet Red Army. Summer Playhouse (CBS, 8-8:30 p.m.): In the comedy ``Baby on Board,'' a couple in their 40s (she's a travel agent; he's a teacher) have their first child and discover they now have few common interests with their childless friends. Not only that - their peers are some 20 years younger. All-Star Baseball (ABC, 8 p.m. ET to conclusion): This 59th summer classic between the National and American leagues is covered live from Riverfront Stadium, Cincinnati. Al Michaels, Jim Palmer, and Tim McCarver announce, with Gary Bender and Joe Morgan doing field interviews.
WEDNESDAY Great Performances: Live from Lincoln Center (PBS, 8-10 p.m.): Gerard Schwarz leads the Mostly Mozart orchestra in the 22nd anniversary of this festival. Pianist Vladimir Feltsman and mezzo Frederica von Stade perform. An Empire of Reason (PBS, 10-11 p.m.): Picture men like these as actors: William F. Buckley Jr., Phil Donahue, New York Governor Mario Cuomo, Walter Cronkite. They and others - in today's idiom and in modern clothes - play historical figures in the 1787-88 debates in New York State over ratifying the US Constitution. Schedules may vary in some time zones. Please check local listings, especially for PBS, where individual stations often air programs on differing days and times.