Experience
My experience has been this:
1. If you travel on the new Autopista through Nagua from POP airport, the total travel time to SDQ is about 2.5 hrs on a slick day (correct hours), and 3.0 - 3.5 hrs to central Santo Domingo on a stupid day.
2. Going through both Puerto Plata and Santiago, the trip to Sto Domongo is about 3.5 - 4.0 hrs (realistically).
Your problems are these: If you take the eastern route (Through Nagua) takes you east of SDQ airport by about 8 KM... The Western route through Puerto Plata and Santiago takes you to the Western end of Santo Domingo on Avenida John F. Kennedy...
If you choose the correct time, the Western route (though longer) can actually take less time to get to central Sto Domingo, say, Avenida 27 de Febrero and Maximo Gomez, where as the Eastern route (taking you cross the NIGHTMARE bridge) gets you to the same spot MUCH quicker on good days and an HOUR later on a bad day).
As far as policia, the Eastern route along the new highway is MUCH better. The trip along the coast road through Puerto Plata, then Santiago City, then la Autopista sur through Bonao to Santo Domingo is a real experience. Taking the more scenic and local Western route, expect to see PN policia all along the highway from Santiago to Bonao, in NEW vehicles (many motocycletas) and if you are unlucky, a roadblock stop in the construction zone north of Bonao... This is both fun and exhilarating if you know the ropes, but can be a nightmare if you are a newbie...
Advice: Take the modern highway south through Nagua from POP airport if you want easy, hassle-free cruising... I am a masochist. I actually enjoy the trip through Bonao... Miguel Fernandez (El Colonel) es mi amigo!!!