STOCK-MARKET PROBLEMS appear not to have effected holiday travel plans, according to Allstate Motor Club. ``The recent volume of requests remains at a steady, high level that is common for this time of year,'' an Allstate spokesman said. Florida holds a big lead over other states as the most inquired-about destination. MARRIOTT IS RATED AGAIN as the ``top hotel chain'' in a survey by Business Travel News. This is the third consecutive year that Marriott Hotels and Resorts has won the honor. The survey quizzed 1,831 corporate travel planners regarding 74 hotel systems. THE NEW CRUISE SHIP ASTOR begins worldwide service Jan. 26, traveling from London to Brazil by way of Portugal and Spain. Prices range from $2,790 to $10,730 per person. An introductory offer features a $500 discount for bookings by Jan. 15.