I don't know about Alan Wake, but I wouldn't get FFXIII until you know for certain you'd like it.
FFXIII has a decent storyline, though nowhere near as good as other games, it takes a VERY long time to beat, but it also has some of the most annoying characters in videogaming history(Vanille, I hate you. And Snow, I hate you too.) And the game picks up after twenty hours, but gets very dull about 3 hours before you can beat the game. I still haven't finished it. So yeah, you should really look it up before you spend the money. I'm still not sure whether I liked FFXIII or not. It had some AWESOME moments, but it also had some very, very, VERY annoying ones.