JR Pass Itinerary

Hi,

I wanted to see if it would be a good idea to get the JR Pass or to just book shinkansen trips and try to find local transit passes. My wife and I will be travelling in Japan from the end of August to mid-September for 21 days.

This is our itinerary:

Flight into Haneda and stay Tokyo (7 Days)
Kyoto (3 Days)
Osaka (3 Days)
Travel by flight to Sapporo (5 Days)
Travel by flight back to Tokyo then go to Shimoyoshia (1 Day)
Then back to Chiba (3 Days) before flying out from Narita