As explained above, the best way to get to Santo Domingo from the east (a four-hour trip) is to take the Expreso Bavaro that departs Friusa-Bavaro (Tel 809 552-1463) at 7am, 10am, 2pm and 4pm. This bus makes a stopover to pick up passengers at the Veron stop at 7:15am, 10:15am, 2:15pm and 4:15pm. Tickets are RD$270, and there is a short stop in La Romana. The bus takes you to the Sitrabapu-Sichoprola terminal at Calle Juan Sanchez Ramirez 31, near the intersection with Maximo Gomez Avenue (Gazcue), Tel 809 682-9670. From Santo Domingo-East, the buses leave at 7, 10, 2 and 4 pm to Veron and Friusa, with an extra daily departure at 2:55pm making a bus stop at Punta Cana International Airport. Seating is first come, first served. Allow at least half an hour before departure time. Take note that on Sundays and holidays, these buses fill up fast.
If you will be traveling on a holiday or Sunday, I recommend you catch the bus at the Friusa stop, because the Veron bus may have filled up at Friusa. The Veron stop would be closer for hotels in the Cabeza de Toro-Punta Cana area.
If you will be traveling on a week day, to be sure, just plan on taking the earlier bus, so if it is full you can take the next one.
Remember you can always take the bus to Higuey, and transfer from there. That one is slower, though, because it makes plenty of stops on the way to Santo Domingo. In Santo Domingo, you get off at the first stop and take a taxi to your hotel.