KIM WRIGHT WILEY wrote the first edition of Walt Disney World with Kids in 1989, and 25 editions later she's exceeded 60 visits to the parks, a statistic that stuns even her.   But her daughter and co-writer LEIGH C.W. JENKINS, who first visited the park at the age of nine months, can surpass even that number of visits.  Leigh's longest visit lasted for two and a half years while she worked at both the Grand Floridian and the Magic Kingdom.