14 or 21 days JR Rail Pass

Hi :-)

I will go to Japan in spring 2016 with my brother. Here our plan:

1. Tokyo
2. Tokyo
3. Tokyo
4. Tokyo
5. Tokyo
6. Kyoto / Osaka (it isn't decided yet if we will stay in Kyoto or Osaka)
7. Kyoto / Osaka
8. Kyoto / Osaka
9. Kyoto / Osaka
10. Kyoto / Osaka
11. Kyoto / Osaka
12. Kyoto / Osaka
13. Hiroshima
14. Hiroshima - Himeji - Nagoya
15. Nagoya
16. Takayama
17. Takayama
18. Takayama / to Matsumoto or Kanazawa (isn't decided yet)
19. Matsumoto or Kanazawa / in the evening to Tokyo
20. Tokyo
21. Tokyo
    (22. Tokyo - probably we could spend a day more in Tokyo)

From Tokyo we will do sidetrips to Hakone, Nikko, Kamakura and Yokohama. From Kyoto or Osaka we plan to do sidetrips to Nara and Kobe and in Hiroshima we will go to Miyajima.

At first I thougt that I could use a 14 JR Rail Pass from day 6 to 19. Or would it be better to use a 21 days rail pass (probably because if we want do another sidetrip to a destination or so).

What do you think? And is this plan good?

I read a lot in Japan-Guide, but I'm not sure if we should choose Matsumoto or Kanazawa. Honestly I really want to see the Matsumoto castle, but I also saw that Kanazawa is a good place.

Thank you very much for your help in advance :-)