The Constitution Day holiday turns the first weekend in November into a long weekend for DR dwellers. Many hotels are offering sales to attract local crowds. The long weekend runs from Friday, 2 November through Monday, 5 November. Constitution Day falls on Tuesday, 6 November, but DR law specifies that it is to be celebrated on the closest Monday.
See http://dr1.com/travel/prepare/holidays.shtml for more information on holidays in the DR.