Define nightlife.
IMO Compass Point is the best choice on the East End if diving is your priority. Certainly it's the most convenient of the the 3 main places to stay if you are diving with Ocean Frontiers onsite, especially if you want to do both the morning and afternoon boats. The units themselves are nice. There is no beach. The original pool was more designed for dive training and wasn't really a good place to hang out and relax, I don't know if that has changed at all with the restaurant opening - don't know if it is just a place people eat or has become a place to hang out (which was needed there.) They added some timeshare units across the road from the water and there is a somewhat nicer pool over there. They can have pretty good package deals with condo/diving/car, don't know if they offer it for 3 days.
I have also stayed at Morritt's and dove with Ocean Frontiers, but only because I had a timeshare to use there. It's fine though my last choice of the 3 places except maybe for the beach. I don't think the units are nearly as nice, and just don't like the atmosphere of the place as much. (There is a section called Morritt's Grand which I get the impression is nicer, but I haven't been in those.)
I have also stayed at the Reef and dove with Ocean Frontiers, simply because Compass Point had barely opened at the time. If someone is looking for a tropical resort rather than a dive resort I think it's the nicest of the 3 in that way, with a nice beach, pools on the beach, landscaping, etc. If there are non-divers along it's a good choice.
Morritt's and the Reef are largish timeshare resorts and have various bars, restaurants, and you will find happy hours and some music/entertainment at night. There are a few restaurants not too far away from these places, and some a bit further drive away. But no real party scene near there that I'm aware of.