I want to take in some sites, go to a beach and scope out some night life....doing this by myself so safety is a concern.
Samana! Las Terrenas is very sanquified, Las Galeras is a little more familiar, but it is also the same Dominican game. At daytime women alone can move everywhere - at crowded places. At nighttime a woman should be careful where to go - except she urgently needs a "special contact" to a Dominican - Samana also became famous for its (female) sex tourismn. But as a woman alone you still can spend beautiful holidays there.
Samana is much cheaper as Punta Cana, and you can do great excursions from there - much better as from Punta Cana.
Saludos