Scubeedu,
I think you will be impressed by the playa dorada complex, and the paradise club in particular. It's one of the nicer properties, with a nice beach area, plenty of food variety, and wonderful grounds! Don't worry about sickness, just be careful about drinking/using purified water. I haven't stayed there myself, but I've visited the property several times, and have friends who enjoyed it immensely. Apparently, the rooms are clean and spacious, but nothing to write home about. Other than that, you should find it to be a wonderful spot!
DR1 suggested many of the "things to see". I've found that a great, convenient, inexpensive way to see many of these sites is to hire a taxi driver to take you for a half day (or full day if you wish) tour of the area. Six of us hired a brand new air conditioned 7 passenger taxi van (you'll see them outside your hotel) with a driver who spoke good english and was a wealth of knowledge for about 600 pesos, for 4 hours! It took a bit of negotiating on the price, but everything does! (shop around, find a driver you like and settle on a price before hand.) Our driver gave us the grand tour of the puerto plata/sosua area, stopped everywhere we wanted him to, gave us as much time as we wanted wherever we stopped, and we had a great relaxing time. I'd recommend it to anyone.
Mark