So a few things:
Haneda (HND) is actually closer to central Tokyo than Narita (NRT) and will cost you less to commute into the city.
The MPE is issued by Chase, but earns you United MileagePlus (UA) miles. Chase-branded cards like the Sapphire, Ink, and Freedom lines earn Ultimate Rewards (“UR”) points, which can be transferred to United miles at a 1 point to 1 mile ratio; or redeemed through the Chase travel portal at a 1 point = $0.0125 value on the CIP (and CSP) or a higher 1 point = $0.015 value on the CSR. In the first option, you are converting UR points to UA miles and using the miles to book award travel with United directly. In the second option, you are treating UR points as cash (subject to your card’s redemption value, the CSR makes the points worth more) and using them to pay for the flights on the Chase travel portal (think of this like Expedia). You have to decide which option uses less points.
So using your screenshot, I think I’ve found the cash value of the tickets vs. the points needed to book the same tickets as award seats.
Your dummy RT economy booking for two is $2,839.42 with taxes and fees, which will cost you 227,154 UR points if you book it through the Chase portal using your CIP (1.25x redemption bonus), or 189,295 UR points if you book it using a CSR (1.5x redemption bonus).
The same flight if booking award travel with United directly is 230,000 UA miles + $103.22. So for this particular flight, booking through the Chase travel portal will be cheaper (less points and out of pocket cash for taxes and fees).
However, I noticed the reason why your award flight is costing so many points is because your DSM>HND leg is 80k UA miles! If you book a Saver Award, it’s only 35k UA miles each way, or 140,000 UA miles + $103.22 for 2 R/T economy tickets, which is waaay less than what you’d pay in UR points on the Chase travel portal.
Then it occurs to me that you might not be seeing the 35k UA miles Saver Awards because those are, as you can see, “exclusively available to you as a MileagePlus Chase cardmember,” which goes back to why having the MPE can really come in handy when booking award travel.
If, say, you and DH each got the MPE cards, even at the lowball public offer of 40k UA miles, then you’d have access to this increased Saver Award availability and each of you would only need to transfer about 30k UR points into 30k UA miles to book a R/T 70k UA miles economy Saver Award.
Hope this helps more than it confuses.