Is 7-day pass the best?

Hi there!

From the sounds of your trip the majority of your travel will be done in and around Tokyo itself. The destinations you list are actually mainly within the general Tokyo area (except Nikko and Odawara), and are not long distance so I think you'll be better off purchasing JR tickets and Metro tickets as needed rather than purchasing a Japan Rail Pass.

I think the NEX + Suica pass is a good options, but you should also look into the unlimited Metro cards that Tokyo Metro offers for foreign visitors (purchase in Narita on arrival). If you do decide to use the Narita Express, you reserve your seat as soon as you purchase your tickets at Narita Airport. If you go for the NEX + Suica deal, then the JR staff will make your seat reservation as part of the process (I've travelled on the NEX many times and it has never been very busy so I'm sure you'll get a seat).

There are many many trains on the Chuo line so it's hard to find an actual timetable. You can look up train timetables and costs for the Chuo line at the Hyperdia travel planning website and learn how to use Hyperdia through our video blog. Here's a sample itinerary from Narita to Nakano for you to get an idea of the trip - it actually looks like the fastest route is via Tokyo station, but your son may be thinking that going via Shinjuku will be a simpler transfer for you to make when you just get off the plane - please confirm with him!

Hope this helps and you have a great time!