1. Use luggage delivery
2. Green Class doesn't always mean more luggage space. In fact higher percentage of Green Class passengers on the Hikari are foreigners (who don't use luggage delivery) and more competition for the luggage space behind the last row.
3. Green Class between Tokyo and Kanazawa are more likely to be sold out than Ordinary Class.
4. Green Class on non-Shinkansen trains, you can almost have the whole cabin to yourself.
5. I had no problem putting mid-size check-in suitcase on the overhead rack, or even in front of me and still have sufficient leg room on shorter trips on the Shinkansen. So for us 2 people travelling = 2 mid-size check-in + 1 roll aboard + 2 backpacks all on the overhead rack, no problem. We rarely use luggage delivery because my hotels are always right next to the station.


>> some trains require an additional "Super Limited Express ticket" plus the JR pass?

I suppose it means "seat reservation" ticket. If you want reserved seats, or seats on "reservation mandatory" trains, you need to get reservation, which is issued as a ticket. For other "Super Limited Express", your JR Pass can be used to get on without anything if you use the non-reserved seats.

Nozomi / Mizuho, you can't get on unless you pay for the full "Super Limited Express ticket" which defeats the saving of buying a JR pass. In fact it would end up costing more than buying a full ticket without a JR pass.