The middle class is only a small part of the population but they all live in Santo Domingo, between Maximo Gomez to Luperon and Kennedy to Sarasota or maybe Independencia. So these 1,000,000 people you are seeing all around you when moving around in the capital.
Santo Domingo has the largest concentration, but there are plenty of middle class households in the interior too. In fact, cities like Santiago and San Francisco de Macor?s are mostly composed of middle class household. La Vega has a very sizeable middle class too, so does Bonao and a host of other cities/towns.
Needless to say that most of the middle class lives in the SD metro area and in the central Cibao with a few islands outside of these areas.
There is a marked difference between the upper middle and the lower middle, with the upper middle being what most people consider 'middle class.'
A simple rule of thumb for knowing where is there a sizeable middle class is to see where are businesses that target this group located and where are they expanding (La Sirena is a perfect example because their stores are not geared for the poor or the rich, but if you ever been to several of their stores you will notice that they are not all the same. What type of products they offer and the overall ambiance of their stores depends on whether the store is in an area of mostly lower middle households or upper middle. In areas with plenty of both, those stores tend to have everything and all the conditions to accommodate the upper and the lower middle classes.)
There are other type of businesses too that should be tale tell signs.
Upper and upper middle class is composed by roughly 2 million people, the lower middle 3 million. The rest are either poor or extremely poor. Country has around 9 million people, give or take.
Upper middle class reaches critical mass in just two cities, Santo Domingo and Santiago. The rest of the middle class has a strong weight in many of the provincial capitals and in a handful of other towns.
For people that live in tourists areas and are only acquainted with these areas, they may feel there's not much of a middle class and the reason is because in tourists areas there isn't much of it.
Another characteristic that many people ignore is that the bulk of the population lives roughly 10% of the land area.