I've never been to Blue Bay.
We have been twice at Riu Bachata (October & December 2006)
Mostly we used the resort as a bed and breakfast, since every day we went out for lunch, dinner, drinks, casinos, etc.
I have to tell you, that, in my opinion, this resort offers you the best for your money. It's not a 4 or 5 star hotel. There's no such a thing on the north coast. Not as long as you pay $50-$60 per person, per day, all included.
The resort is very clean, so are the rooms, the gardens, the pool and the beach.
All of the employees (in our 2 trips) were excellent.
Do not expect gourmet food (nobody can when you pay those prices) however, I must tell you the buffet is excellent (pricewise).
I'm explaining our experience, as a middle aged couple. Maybe, if you are single, this is not the best place to stay. But I can assure you, that you are not going to get any better for your money, as far as accommodations, clean rooms, service, etc. etc.
If you are casino people, you have Ocean World only 2 miles away from you, right at Cofresi beach, where you will enjoy quite a few good restaurants as well.
I have been several times to Playa Dorada, and in my opinion, Riu beats all of them by a mile.