I understand your question perfectly, as there are so many amazing places in the Dominican Republic to get married that are not just beach locations, or gazebo.
This country has amazing mountains and rivers. Waterfalls and attractions. I can't imagine making a choice would be easy but think about the fact that this is your most special day and do something memorable. Anyone can get married on a beach or a big resort, most do, but you could do so many more things with a destination wedding.
Have you thought about a private villa rental for your special day? Maybe something over-looking the ocean, all decorated up?
Maybe a tropical garden in a park or eco-lodge?
There are so man options and the Dominican Republic is full of ideas. I currently live here, so if you have questions, feel free to ask.
Wishing you all the best for your wedding.