Trip this August - do you recommend a 14 or 21 day pass?

Hi we are coming to Japan this August, itinerary as per below - would you recommend a 14 day or 21 day pass?
Land Haneda travel direct to Kyoto same day, stay 4 nights
Depart Kyoto AM day 5 to Beppu for 3 nights
depart Beppu AM day 8 to Osaka for 4 nights
Depart Osaka AM day 12 to Fuji for 2 nights
Depart Fuji AM day 14 to Tokyo for 6 nights
Depart Tokyo to Haneda airport AM day 20

was thinking a 14 day pass to get to Tokyo then use metro / mono rail around Tokyo and back to airport - what would you recommend?
also can you reserve seats before activating the pass?