Stayed at Riu last year and are going back again in a few days.
Personally, as an "ex party animal" I wouldn't say that the nightlife at Riu is great. Yes, there's one 'nightclub' that is open until 2am, bars tend to close at midnight (I think it was) and reopen at 10am.
The entertainment team come round once or twice a week and offer a free shuttle to margaritaville ($20)pp.
From what I've learnt, for the livelier souls, it's better to stay on 7 mile beach (Riu Club is at the far end of bloody bay) there is nothing after the Riu Club apart from 5 or 6 new build stunning houses (were almost finished last year).
It depends how much you like to party. Personally, I'm "all grown up" now and am returning to the Riu to get married to my calming better half lol.
Anyway, I have waffled on enough. Have a great time. Bottom line, no matter where you are you will have fun. It depends on the individual!
Have fun x