We planned Tokyo, Osaka, Kyoto, Takayama (but we nixed Takayama after a heavy night of too much hanami) and Nikko. All pretty touristy we thought. After a bit of searching we found Mount Koyasan, a magical little place in the mountains which is the center of Shingon Buddhism, and a bit off the tourist trail. This mountain town is covered with temples, some 50+ temples cover the area around Mount Koya! Spread out between the temples is one of the oldest cemeteries in Japan.
We had 2 days to kill before we met friends in Osaka and Koyasan was the perfect 1-2 day getaway. Koyasan is located in Wakayama Prefecture and is about 2.5 hours from Osaka Namba station.
If you do find yourself in the Koyasan area, check out Kokuu Guesthouse for a great stay. It feels more like a boutique hostel. It's a wee bit pricier than any other hostel you'll stay in but the Japanese owners make a delicious breakfast and Indian food from scratch (they backpacked around India so it's the real deal!).