I would say that there is more of a selection in Santo Domingo, bigger upscale appliance stores, for instance, more US and European brands if that is what you?re looking for. But Santiago has all of the basics, and for things typically used by Dominicans, the prices are the same. Examples: fans, stoves/ovens, beds, etc. Ochoa on Feb 27 has appliances, lighting, outdoor furniture, office furniture, BBq?s, etc. Just check the pricing before tossing it in your cart. <but if you are looking for a specialty item, like a waterbed for example, or a very special light or subzero refridgeration, Santo Domingo.
One place I would definitely check is the highway out of Santiago to the south. Loads of local made furniture, and some pretty sweet bamboo beds on the east side of the highway, good prices.