Planning our first trip to Dominican Republic

[Howkard]

We've done Jamaica, Barbados, St. Lucia, hit up a bunch of Caribbean spots over the years. Somehow never made it to the Dominican Republic though, and that's about to change in two weeks. Neither of us are beach loungers, couple hours max and we're ready to see actual stuff. Where should we be driving to, what's actually worth the trip? And yeah, where do we grab a rental car that won't screw us over?