Constitution Day falls on Wednesday, 6 November this year, but the holiday will be celebrated on Monday, 4 November. This makes for the long weekend of Friday, 1, Saturday, 2, Sunday, 3 November and Monday 4 November.
This is not the last long weekend of the year – there is still the Christmas holiday coming up.
This year Christmas Day, 25 December, falls on a Wednesday, so expect little to get done the previous week, except for lots of shopping and partying. In the Dominican Republic, Christmas Eve, 24 December, is not an official holiday, but for many not working in the entertainment, tourism or commercial sectors, it will be a day companies give their workers off to prepare the traditional Christmas dinner.
For more on holidays in the Dominican Republic, see http://dr1.com/travel/prepare/holidays.shtml