Koenji is great too but I still prefer(red) Shimokitazawa. The central area feels more compact to me instead of just being one long street running between Koenji Station and Shin-Koenji Station.

In general, I find it interesting that folks aren't just hitting the usual sights of the Imperial Palace, Sensoji and the Shibuya scramble crossing. Travellers are getting more savvy and I think the desire for that "unique" Instagram shot is driving visitors to branch out a bit.