Comparing currencies is a bit like dollars and pesos. UR is considered one of the most valuable currencies, and Hilton is one of the weakest per point. 1 UR point used on your CIP through the UR travel portal is worth 1.25 cents (and 1.5 cents on the CSR); by comparison, most people value Hilton points somewhere around 0.4 cents per point. It takes a lot more Hilton points to book what you could book with UR.
Let's do some early morning math.
15,280 UR x 0.0125 = $191/night. 73,721 x 0.0125 = $921.51/4 nights. With Chase UR, you're getting a fixed $0.0125 per point redemption value.
Let's use these numbers to compare with Hilton points.
$191/66,000 = $0.0029 per point on a 1 night reservation. $921.51/264,000 = $0.0035 per point on a 4 night reservation
@Haley R remarked that 66k/night seems a bit high, but you're getting 0.3-0.35 cents per point on the redemption using Hilton points, which is not totally off from what most people value Hilton points.
Now, there may be good reasons to book with Hilton points vs. Chase UR points.
Booking via Chase UR is effectively booking through Expedia, a third-party online
travel agent, and you likely will not receive the benefits of any elite status you may have. As you know, the Hilton Biz and Hilton Surpass cards come with Hilton Honors Gold status. Gold status will get you complimentary breakfast and might get you a room upgrade. The Hilton Aspire card comes with Diamond status, which is Hilton's highest elite tier and gets you free breakfast, room upgrades up to a suite when available, lounge access, and apparently access to the Hilton Tokyo Bay's guest services manager who can charge park tickets to your room. Booking with Hilton points will get you the benefits of your status.
Have you considered spending 5 nights at the Tokyo Hilton Bay? I know the location isn't ideal for traveling around and seeing the rest of Tokyo. However, you're already planning to stay 4 nights. Booking through Hilton points will get you the 5th night free. You do not get a 5th night free by booking through the Chase UR portal. Let's do some math again.
$191/66,000 = $0.0029 per point on a 1 night reservation. $921.51+191 ($1,112.51 for 5 nights)/264,000 = $0.0042 per point on a 5 night reservation, and that's where most people value Hilton points.
264,000 Hilton points may seem like a lot, but that's basically two Hilton cards. The Hilton Biz and Hilton Surpass are regularly offering a 125,000 points SUB. If you go with the Hilton Biz, that doesn't count against 5/24. The Hilton Aspire regularly comes with a 150,000 points SUB. If you were to get any mix of 2 Hilton Biz, Hilton Surpass, Hilton Aspire, you're set; or if you get 1 and P2 gets 1, Hilton makes it really easy to pool the points you'd get from the SUBs. Also remember that Amex expects you to continue spending on their cards after you've met MSR and gotten the SUB, which is fine for the Hilton Biz and Hilton Surpass because both these cards award a Free Weekend Night certificate when you've spent $15,000 on the card in a calendar year, and you can apply these certificates to a weekend night (Friday, Saturday, or Sunday) during your stay.