We have a group of 24 of us going to PP next week and if you are still here, I can let you know about the Pub Crawl, catamaran, scuba, waterfalls, OceanWorld and more.
There are many good tour companies in the area and from recommendations we are going with Isaira Tours. They are taking 6-8 of us girls out one day to visit a school and then a few hours in Sosua to shop and visit Checkpoint. total cost of $35ish for 8 of us for 4-5 hours!! NICE
The following day we hired him to take 20 of us on an all day tour, drinks included on bus and also lunch with a cocktail at a nice restaurant. We visit the San Filippe Fort, rum factory, amber, factory, cigar shop, grocery store, a couple poor villages and back to Sosua for a couple hours in the afternoon for around $35 pp 9-4 (or whenever we are done) - We knocked off the school, sugar cane factory and the synagogue They are also letting us design our entire day and are looking to stop at some other historical sites as well.
I personally would secure your 1/2 day or full day tour ahead of time with a private company, although I have heard many good things about some of the cab drivers as well. I would just get someone is recommended here and on other DR web forums
If you are still here when we get back on the 17th - I will let you know all about it.