Should I get a JR Pass?

Hi,

I'm wondering if it's worth getting a JR pass for my ~20-day trip to Japan in April.

This is my itinerary:

Narita Airport > Tokyo (3 nights) > Kyoto (2 nights) > Osaka (3 nights) with a side trip to Nara > Kanazawa (2 nights) >Toyama (2 nights) > Ainokura (1 night) > Tokyo (4 nights) > Haneda Airport

I know some of these areas are not accessible by any JR trains/buses (ex. Ainokura) but would a JR pass at least make sense for the first half of the trip?

I've never travelled to Japan before and I'm overwhelmed by the various transportation and payment options!! =O

Any help is appreciated...thanks!! ^_^