We did this last year and really enjoyed it. The guides were really good and it was well organized. It was a short walk from the pier to the jeeps. They put 4 people to a jeep which worked well for us since we were already a party of 4. They verify licenses before you leave to see who is eligible to drive. You can decide who drives in your party. If it's 2 couples, I think they usually switch off, one coming and one going. But that's up to you. We drove in a line and they had vehicles placed behind in case someone missed the lights but it seemed to go pretty smooth. We visited a small ancient ruins area and drove down a fairly long path through the park and to the beach area in Punta Sur. From there, we had a guided snorkeling tour and afterwards there was a nice lunch served on the beach. They had tables set up for different sized parties. If you didn't want to snorkel, you could just hang out on the each. Afterwards, we headed back and stopped at a lighthouse. You could climb if you want. There were also some small gift shops. The view from the lighthouse was pretty neat. I attached a few photos for reference. Driving through the park to the beach, the beach area and the view from the lighthouse. You can see all of the jeeps lined up below.
We would definitely do this one again. I will note the snorkeling is tough. Definitely use the fins they offer. Most people did fine but there was someone who thought she didn't need them and they ended up having to tow her back to the shore.