Dominican Republic is also part of the Hague convention so similarly like Colombia all documents need to have an Apostille. The only differences so far that I have noticed is the fact that Colombia requires documents to be less than 30 days old. For example you must get a new birth certificate from Vital Statistics and then have it Apostilled and the marriage has to be within that 30 day period.
The marriage will be in January so it should leave enough time to get these docs done prior to the trip. So much for a quick Las Vegas style wedding. In fact the only place I have encountered to offer a quick style wedding like that is in San Andres, Colombia. For that reason many men marrying in Colombia, after learning what is entailed for a normal civil marriage just opt to take a flight over to San Andres with the passport from both and it’s a done deal. Not to mention weddings in San Andres are really cool, usually right on the white sand. It’s perfect for those of you that have by freak chance just ran into a Colombian girl that you just feel like you need to marry that same week. Otherwise, you have to fly home, order all the docs then later send them off for Apostille, then fly back to Colombia and be married within 30 days of the doc dates.
The San Andres thing might end up costing you an arm and leg since you may have to fly the family over as well, plus the rooms for everyone.
My advice is to talk her into eloping and just have a party upon return.