Out of Washington but never out of the spotlight, Senator Hillary Rodham Clinton, her husband, former president Bill Clinton, and daughter, Chelsea, are expected to arrive for a Vineyard vacation on Saturday. The Clintons have been regular Vineyard visitors, but it was their visit in August 1993, during Mr. Clinton’s first term in office, that attracted the most attention. Attention these days is on Mrs. Clinton, now a popular U.S. senator from New York, a best selling author, and if political pundits are correct, a future Democratic presidential candidate. In her only scheduled public appearance, Mrs. Clinton will sign copies...