Although San Francisco this weekend opened Treasure Island for a "Blues & Art in the Bay" festival, it will be some time before tourists can make regular visits to the former Navy station, which sports great city views but so far little else. The tiny island will remain closed to the public while the city considers what to do with it, the mayor's office said last week. . . . The 1922 building where the Greater London Council met until 1986 has been refurbished as a hotel, retaining its original members' library, fireplaces and other features. Rates at the 200-room London Marriott Hotel County Hall begin at about $340 per night. Reservations: (800) 228-9290. . . . The Van Gogh Museum in Amsterdam closed last week for a seven-month renovation and construction of a new wing. A portion of the collection will remain on display during the work, which is expected to be finished by April 1, 1999. . . . Cathay Pacific Airways flights will become totally smoke-free on Oct. 25, when the airline makes flights between Japan and Hong Kong nonsmoking. . . . Last year was the most profitable ever for the U.S. lodging industry, which grossed $17 billion in pretax dollars--nearly 40% more than in 1996, according to the American Hotel & Motel Assn.