12 Days in Japan

Hello,

Given the following itinerary what would be the advantage of buying a JR 7-day vs. a 14-day pass?

April 7-11 (4 nights): TOKYO - Explore
April 11-12 (1 night): Lake Kawaguchiko area (to see Mt Fuji - ovenight stay)
April 12-16 (4 nights) : KYOTO - take 1 Day trip to Osaka; 1 Day trip to Nara
April 16-17 (1 night): Hiroshima, explore and overnight in Miyajima at a Ryokan
April 17-19 (2 nights) return to TOKYO - Explore TOKYO; April 19 - Depart from Narita early afternoon

Your input will be much appreciated!

Thanks.