2-night trip to Nikko from Tokyo

I'm travelling from Tokyo to Nikko with my son (aged 15) on 1st April, leaving on 3rd April (heading for Kyoto). I plan to buy a 7 day JR rail pass, which will start on 3rd April, i.e. the day we leave Nikko.

I am aware there are various passes available, but which one would be best is confusing, as none quite fits my plan! As I am activating the JR pass on the return journey I guess I don't need the return train ticket (though I think at least part of the journey is not with JR?). I am looking for the best budget option, but when I look on Hyperdia the train fares are much higher than what i've seen quoted elsewhere, and a single fare often looks more expensive than the Nikko passes. I don't mind the trip taking a little longer - just as long as all the changes aren't too confusing.

During our stay I'd like to get to Lake Chuzenji, but I'm not sure if I'd take advantage of the other Nikko All Area Pass attractions.

Any advice would be gratefully received!

So why not pay the single fare ticket on Tobu rail to get to Nikko and use your JR pass for the JR Nikko line to Utsunomia and then to wherever you are going. Both JR and Tobu are around two hours Tokyo/Nikko one way, but the JR cost (with shinkansen) is a bit over Y5,000 while the Tobu rail is about half that (I haven't bothered to look it up).
In Nikko you could vet the Y2,000 bus pass (covers two days) and that offere a saving even if all you use it for is one round trip to the lake.