Currently reading the 3rd book. I'm curious to see where they leave off in season 3 since they are going to split the book into 2 seasons (at least that's what I heard).
Spoiler (Click to reveal/hide)
As far as I've read I've made it through the Red Wedding. I don't know what comes next obviously but I would imagine they would end somewhere around that. But in the book so far there hasn't been a ton of Joffrey so I could see them picking and choosing the stories/timelines to fit with the TV show.