Two resorts, same ownership, share Esmeralda Beach. We ourselves stayed at Sol Rio de Luna y Mares, which is a four star. The price for a week was just over $1000(CDN) for us. Food was quite good for Cuban and the staff are very friendly. Note, the rooms are more three star but very clean. We've been there twice now and will likely go back again at some point.
The other hotel is called Paradisus Rio de Oro, a five star, which usually goes for around $1500+ for seven days. I talked to a few people that have stayed there and they say it is exceptional for Cuba- nice rooms, good food, attractive grounds and excellent service. As mentioned, they share the same beach, although I think Sol Rio de Luna y Mares actually gets the bigger and nicer end. If you can get a good deal at Parradisus- go for it, otherwise Sol Rio Luna/Mares is very good value in that price range.
There used to be dive shop on Esmeralda beach, but last Fall (2010) they moved the shop to Pesquero beach which is a 10-15 mins bus ride. The shop has its own van and makes pick-ups twice every morning except sunday. There is also another dive shop at Guardalvaca beach, but 'I think' you would have to find your own way there- $5CUC's each way.
Note: diving is not included as part of the Sol Rio package, just the Paradissus. Hope this helps!
