Dave,
What kind of Fishing? Off-shore? Bottom? inshore? Fresh?
For Off-shore the Sousa,PP, Caberete area is not the best. The best action for that can be found off the eastcoast, Punta Cana, Cabeza de Toro Area.
For inshore action(Tarpon) head West to the Montecristi Area. Or east to Samana bay. For much better inshore action(Tarpon, Snook, Bonefish) you have to hit the South Coast.
Bottom Fishing is nothing to write home about anywhere in the RD.
There is suprising good Fresh-water fishing in some of the various reservoirs in the interior of the country.