It's been about 20 years since Susan Isaacs's most successful bestseller, Compromising Positions, was published, and apparently her fans are happy to see the return of the book's heroine, Judith Singer, in the author's latest top seller, Long Time No See . HarperCollins rolled out the book with a 138,000-copy first printing and a 24-city tour that ends with stops at about 10 Jewish book fairs (that leg of her tour begins October 30 in Houston and ends December 5 in New York City).