We stayed at the RIU Mambo - and it was nice. There wasn't a hair dryer in the room, but if you leave a US$10.00 refundable deposit with reception they will provide you with a hairdryer. I also requested an iron and have to leave an addt'l US$10.00 refundable deposit. I don't remember if they provide shampoo/conditiner, but I do remember they provide hand soap and a shower cap.
You can tour the entire complex - enjoy any of the pools , bars, breakfast and lunch at any of the 3 (Mambo, Merengue, Bachata) hotels...however dinner is exclusive to your hotel, as there is assigned seating. They also have a snack bar at some of the bars that is open from morning to night.
There are shows, performed by the Animation Staff in the evenings and there is one discotec on the property (located between the Mambo and Merengue). We didn't like the disco and ventured into the city for nightlife as well as other misc. adventures.
There is also a street called "Calle Carribena", between the Merengue and Bachata, which has small shops where you can buy soveniers (a bit over priced but extremely convenient). The pool hall, gym and spa are also located on this street as well. The Casino can also be reach from this street (it is located in the Bachata next to the reception).
All other misc info was obtained from reception. They call the cabs for you when you want to leave the complex - you do pay the higher rate, but it is reliable. Everyone is extremely helpful, just ask.
Hope this was helpful.