The Purge1/2 sounds interesting, although it does seem to have a little bit unique aspect to it. The zombie thing has been done quit a bit but you may prove to bring something new. I'd like to read it when your done. To me what makes a good zombie movie/book is to show more than just the rampage of the zombies but a human side or comedy (Shaun of the Dead) the story. Most movies seem to pull it off kinda bad (Dawn of the dead, Resident evil 2[dunno if it counts], [1 was alright] and a couple others I can't think of). Although I haven't read any books may seem why.