If you said "extremely complicated plot spreadsheet" you'd be correct. I'm going to probably cut half or more of the existing text, shuffle plot elements all over the place, trim at least 10,000 words, and reduce the number of chapters from 55 to 26 (about). I'm tracking three main subplots throughout.
I guess I didn't shake my old habits as much as I thought :)
As I've worked on my own plots, I've always wondered how Rowling did it. I've read her interviews, and I even watched Oprah to see if I could get any glimpse into Rowling's actual process. For one thing, I'm weird like that. I'm endlessly fascinated by how writers work. For another, whatever else you can say about her books, they are complexly plotted. One might even say brilliantly.
So today on Twitter, guess what pops up? A page from the "spreadsheet" Rowling developed while she was writing Order of Phoenix (at least I'm guessing). And check it out! This is how you plot a 4,000-page book with dozens of characters and too many subplots to mention ...