Can only point you to the International Airline Program for American Express Customers who pay the annual premium fee.

It seems to allow discount Business flights (and 2for1 offers) on certain flights including JAL.

Here’s a recent post:

USA International Airline Program (IAP) relaunched as discount benefit (2017).

Other forum regulars know more about the Amex IAP deals.

As for wheelchair experience within Tokyo, that’s a topic I’m familiar with. I recommend it, BUT, ramp and elevator routes are longer and there is more waiting and queuing involved than what others will experience. If two days would feel frantic and rushed for an able bodied tourist, it will be even more so for someone in a wheelchair. I don’t how many of the other cruise destinations will be as accessible as Tokyo, I’d recommend making the most of the city since it does allow exploration.