For those in the NYC metro area, this would be a better comparison IMHO. Santo Domingo is like Manhattan and the Bronx whereas Santiago is like White Plains.
I have been to both cities and personally I like Santiago much better for a variety of reasons.
I think its more like comparing Brooklyn and the Bronx (Santo Domingo) to
Boston (Santiago)....
About 3 hr drives more or less and similar population comparisons in that Bronx and Brooklyn are 5x-6x larger populations than Boston as Santo Domingo is 5x-6x larger than Santiago. Furthermore, they both have huge baseball rivalries!
Also Santo Domingo is South of Santiago as the Bronx and Brooklyn are south of Boston...