I was in Santiago for one night 11 Dec., went to Montezuma and all the bars around Monumento (for food and drinks). As it was Sunday night it was very quite around there (although lots of street parties above near and around the main monumento). But a couple of blocks further down the street I found some bars with lots of down to earth locals dancing and drinking which I found more interesting. As it was my first time and only one night, just watched and have a few drinks and moved on.
One thing you notice immidiately in Santiago (and I guess in DR) is that they like their music VERY VERY loud over there !?
Generally speaking on Sunday (day and night) there was no tourists in Santiago, saw a few on Monday morning though.