Dunno if the druids bother heading there on Samhain. They might. If so there's some entertainment for you :-) With it being a bank holiday it should be busy.

I hate going up there on special occasions though, because I end up getting tetchy with all the idiots that light fires all over the hill.

Lough Gur is a good choice if you're down that way, but you might consider Duntryleague. What a view to the north you get there! In fact I might just do that instead :-)