Nikko day trip and what to places to visit

I will be visiting Japan for the first time in early October for 12 night 13 days. I heard Nikko is one of the best place to see autumn leaf colour change.
I plan to purchase 14 day jR pass.
-Narita airport will be the landing and the departure point; I will stay in Tokyo for 4 full days but would like to make side trips to nearby city like Yokohama and tourist spot such as Nikko.
-what would be the balance itinerary for a day trip to Nikko ?
- latest transportation back to Tokyo from Nikko?
-is it worth to buy JR pass if it is not valid for Tobu rail to travel to Nikko?
- what are the benefits to purchase JR pass for 14 days? I plan to travel to Kyoto during my stay as well with JR I will be visiting Japan for the first time in early October for 12 night 13 days. I heard Nikko is one of the best place to see autumn leaf colour change.
I plan to purchase 14 day jR pass.
-Narita airport will be the landing and the departure point; I will stay in Tokyo for 4 full days but would like to make side trips to nearby city like Yokohama and tourist spot such as Nikko.
-what would be the balance itinerary for a day trip to Nikko ?
- latest transportation back to Tokyo from Nikko?
-is it worth to buy JR pass if it is not valid for Tobu rail to travel to Nikko?
- what are the benefits to purchase JR pass for 14 days? Can it be used to travel to Kyoto round trip fro Tokyo?

The 14-day Pass would probably not pay off, but if you are going to Kyoto and back a 7-day Pass, activated at the right time, would pay off (a round-trip between Tokyo and the Kansai area is roughly the cost of a 7-day Pass).

You are correct that Tobu is the main way to get to Nikko. Check the Nikko guide on this page for rough transportation times and costs, and then use Hyperdia (hyperdia.com/en) to work out your actual travel time and cost. Tobu has a lot of pass options for Nikko, so be sure to check them out.

If you have plans to
1. Go to Kanazawa and Hiroshima ontop of your current itinerary
2. Go to Eastern Japan like Hirosaki or Sendai ontop of ...

Then a 14 day Pass would be a good deal.

The main benefits of the pass besides any cost savings are:
1. Queue once to get the pass, never have to queue again
2. Can make seat reservations for free
3. You can just walk through the gates like a boss

So manly a time saving ability

Thank you for the response

Just to be sure, JR Pass is "Japan Rail" Pass (NOT "Japan" Rail Pass), meaning it is valid on that railway company's trains, which include the inter-city Shinkansen limited express trains, and the pass makes sense if you make some long-distance (inter-city) travels on JR Shinkansen trains.

If you plan your itinerary so that your Tokyo - Kyoto - Tokyo travel falls within a 7-day period, then a 7-day pass will pay off.

If you plan your itinerary to include Tokyo - Kyoto/Osaka - Hiroshima - back to Tokyo, then a 14-day pass will pay off. This is the "guideline."

So if you are staying entirely around Tokyo and only making a trip to Nikko, then it is better not to buy a JR Pass. If you are going to Kyoto and back, then a 7-day pass.