I'd say go to St. Lawrence Gap as the others staetd in the evening. The Boatyard isn't very exciting on a Sunday from what I remember. The best thing I can recommend is listen to the local radio stations to find out what's happening at night (they often advertise the various nightly events if anything is going on). If you're staying in Ch Church, you can go to Club Extreme(I'm not sure your age, but if you're under 30, you may enjoy it.) You can hang out at the beach bars from late afternoon into evening along the coast. Depending on when you are going there could be special events going on. World Cup Cricket, for instance, is soon approaching, so there may be more nightly events in the coming weeks. Ch Church is very central and there are sports bars nearby as well. The Lucky Horseshoe is open 24 hrs if you need a bite to eat and don't want to travel far. Also feel free to take in a drink at a local rum shop. Often times the locals will tell you their preference (though they may tell you that hanging out at the rum shop is all you need).