First-time itinerary advice

Hi all, my girlfriend and I are going to Japan for the first time for 17 days next summer – very excited! I’ve done some research and come up with an itinerary, but would appreciate any tips or advice.

Days 1-4 – Tokyo, with day trip to Kawaguchi

Day 5 – Tokyo to Takayama

Day 6 – Takayama

Day 7 – Takayama to Kanazawa, via Shirakawa

Day 8 – Kanazawa

Day 9 – Kanazawa to Kyoto

Day 10-11 – Kyoto

Day 12 – Kyoto to Hiroshima

Day 13 – Hiroshima to Osaka, via Himeji castle

Day 14-15 – Osaka, with day trip to Nara

Day 16 – Osaka to Hakone for onsen

Day 17 – Hakone to Tokyo for departure

Specific questions:
– is this itinerary too rushed? Should we stick to fewer places for longer?
– should we stay over in Kawaguchi for Fuji views?
– we’ve heard good things about Koyasan, should we be staying there one night?
– is Hiroshima better as a day trip? There doesn’t seem much apart from the museum and Miyajima shrine.

But appreciate any thoughts or advice – thanks!

by PureRefrigerator2013