So, I'm pretty sure that I'll go for it and the only question at this stage is what will I be writing come November. Planning isn't a must, I wrote my first NaNo-Novel with only a rather vague plot idea in mind, but I found over the years that it pays to have some idea where it's all going, otherwise chances are that it'll end up somewhere quite weird and not necessarily to my liking. Not that couldn't happen even with planning. It certainly has happened before. Time pressure makes for weird novels.
As always I will be writing fanfiction. I couldn't write original fiction to save my life. I have a couple of plot ideas whirling around my head for various fandom. I probably like the idea I have for a Paul Temple story most, but I'm a bit wary of writing anything set significantly (as in more than 10 years) in the past. I tried to write a Magnificent 7 story a few years back and failed spectacularily and would like to think that I've learned my lesson: do not write stories set before you were born! Even a story set a few years after I was born still gave me quite the headache as I had to figure out how the characters could effectively investigate a crime without mobile phones and DNA tests. A Paul Temple story would pose similar problems. Another idea is for a Diagnosis Murder story. There are a lot of interesting dynamics to be explored on this and it wouldn't have to be set too far in the past as to require research. However, my plot bunny for this one is a rather lame and not overly original. Well, everything has been done before in a way, especially when it comes to fanfic, but I still like to try for a bit of originality. My other ideas are either exceedingly vague or probably won't yield anywhere near 50,000 words worth of story.