Well, the boys and Danny Williams are pretty much in St. John's, I think. Gotta tell you, you're probably not gonna be told about the boys' hangouts here :) They like their privacy, and why shouldn't they? I will say, though, St. John's is a fairly small town - you're bound to see at least one of them sooner or later.
As for Danny W., couldn't tell you where he hangs out, but I will tell you that, if you're lucky enough to bump into him, go over and say hi - he's really nice. It happened to me and a friend of mine one time in a St. John's pub, and he was super-friendly. I also heard stories from others that he's always like that. (Actually, that was the same night I met Alan for the first time. Alan Doyle and Danny Williams, one night, one pub, post-GBS show. I turned to my friend and said "Well, there's nowhere to go from here but down.")
If you do go to St. John's, you should look up Jolly Rovin' Tours - it's a tour company started by a friend of mine, Sandy (also a member of this board, from time to time :) - she moved to St. John's from away and is a pretty well-known lady in the community now :) She'll show and tell you pretty much all you need to know :)
Enjoy NL - I've been to a lot of places in the world, and that one's probably my favorite :)