The best time to visit Santo Domingo is between November and March. That's when this city experiences its best beach weather, even if there aren't any great beaches to enjoy it on. April to July also makes a nice to time for travel, but at all costs you should avoid this area during the hurricane season, from August to October.
Advance booking is the best way to get cheap flight to Santo Domingo. Book 3 to 6 week in advance to grab cheap flights. Airlines such as Jetblue Airways, American Airlines, Copa and US Aireays offers great discounts on airline tickets. From the Airport you can take Taxi or Bus to the City.