The greenhouse would be an excellent place for a spooky party, just add some gloomy lighting and a few cobwebs. I'm sure Mason won't leave out a Fanged Geranium or Chomping Cabbage plant (nor would any students setting up add any) for added mood.

I am very down for a party at Hogwarts, and I'm pretty sure the majority of students are under 5th year so it makes little sense to exclude them right now. Unless an enterprising 1st-3rd year writer is up for organizing another one.

Seneca Lestrange, I didn't see your post until I posted. I don't know what Book Club president Lottie Whymper would do to organize anything, but I do feel like they'd be reading a themed book for the month at least. I love the idea of clubs having something to do this month.