How the Other Half Gives
By Geraldine Fabrikant and Shelby White
While some best-paid corporate executives, such as William H Gates and Ted Turner, advertise their donations, others, such as John F Welch of General Electric, say their giving is no one else's business; with huge sums that many chief executives earn, they are increasingly seen as standard-setters in philanthrophy; survey of charitable giving of 12 of best-paid executives of nation's 500 biggest companies focuses on Michael D Eisner of Walt Disney Co, Sanford I Weill of Citigroup, Eugene I Isenberg of Nabors Industries, Eckhard Pfeiffer of Compaq Computer, Reuben Mark of Colgate-Palmolive, Eli Broad of SunAmerica, Charles A Heimbold Jr of Bristol-Myers Squibb, Stephen M Case of America Online, Lawrence A Bossidy of Allied-Signal, and Summerfield K Johnston Jr of Coca-Cola Enterprises; photos; biographical sketches and chart on corporate compensation (L)