It's a simple matter of cost vs. convenience. If you have several going you would save by renting a large car or van. Keep in mind that although it doesn't look that far on the map, it is an all day drive (each way) . Your cost for 2 days rental and gas would probably be about US300. If you can do the same day round trip on the plane, leaving PP at 7:15 and returning at 6:15 its US120 each. If you drive, you would no doubt need accomodations in Punta Cana for a night, which is fine if you aren't locked into your hotel in PP. Otherwise you will be paying for 2 rooms that night, and the plane looks like a better deal.
Sweetdbt is correct & hit the nail on the head. I've done it by car & by bus; the car is more expensive; but if ? persons split the cost. it works out. The busese are good from POP to SD; then - ? Regardless, it's both a full & tiring day. No easy & fast way to do it, other than air. Safe journey.