I've stayed at four AI's in PC. RIU Palace Punta Cana, (There are several RIU properties near each other, and TWO Palace's... I was at the Palace PUNTA CANA), Dreams Palm Beach, Barcelo Dominican Beach, and Princess something...(I forget the exact name.) Of the four, The RIU Palace had the best drinks and alcohol service overall, (top shelf brands included). The self-serve liquor bar in the rooms is very convenient too. Of the four, my accommodations at the Dreams resort were the best, they upgraded me to a ocean front room in the exclusive club section, (I still don't know why... I was just lucky). Their alcohol service was close to the RIU's but not quite as good. The Dreams resort was a little more tailored to U.S. guests than the others, (but I don't think that's necessarily a good thing, just an observation). As for ala carte dining, the RIU was a little more difficult. You need to make reservations in the a.m. for that evening's dinner (the popular restaurants fill up fast).
Overall, I think you would have a great experience at either the RIU or Dreams, but personally I'd lean more toward the RIU Palace (and the decor there is really nice too). One thing I will say, you need to pay careful attention to the specific hotel names... they can sound alike and get confusing. The other thing is that in my experience, you do get what you pay for, since the more expensive properties do have better food and drinks. Though, I'd say that the service is similar everywhere, and has more to do with the guest's attitude than the price level of the hotel. You just have to remember a smile is worth its weight in gold, or at least pesos, lol; and the D.R. is a different country with a different culture and different sensibilities.
One more note: On the flight to P.C. this past August, I read in the U.S.Airways magazine that the Paradisus Palma Real was voted the BEST A.I. Resort in the WORLD. Not in the D.R., but the whole world.