There are many places to hobby in Dom Republic. In the town were I usually go (Sosua) you can expect or should deal $40.00 for Short Term or $80.00 overnight. Resort are out of the question for bringing company, and you would have to do your deed outside the resort. You will find all ages range from 18 to late 30. There could be younger that will offer their service, but dealing with those is the fasted way to end up in jail and you don't want to go there.
A plane trip (only) will cost you $928.00 (as per today's price, while a week in a resort will cost you (also as per today's price $863 to $1,010) go figure out why? For the evening were you want an overnight should you stay at a resort, a good hotel will cost you between $55.00 to $75.00 per night, you can have cheaper but not sure you would like them. Most of the bar and beach outside the Resort are within a 10/15 minutes walking distance. Or if you don't mind seating in the back of a crazy motorcycle driver swerving trough traffic, there are always Motoconcho, which would cost you $4.00/$5.00 to go were you want to. Taxi will be $6.00 to $10.00.
For the girls choice is usually good and plenty of opportunity. Only word of advice, don't get drunk to the point of not knowing what you are doing, specially if you don't have a wingman, respect the locals, and you should have a lot of fun. If you need additional info, just P.M. me.