You know, I keep forgetting that you know about this stuff. Just because you're not so into it now doesn't mean that you weren't raised with a good knowledge of it. Hallel, yeah, that'd be fun too, but it doesn't come up that often. Also, basically everyone sings it anyway, so I wouldn't necessarily have tons to add to the usual. (Not that the whole point is to add things, but it's a lot of fun...)