I'm seeing points rates for the Westin Whistler at 130k points per night (is that what they're charging for a
suite?). The Westin Whistler is a Cat 7 hotel with standard points redemption at 60k/night. What rate are you seeing? It sounds like you've already made a points advance reservation? Probably a good idea before peak pricing is introduced.
It looks like you're 2/24. The CIP and Amex Hilton Biz don't count as they are business cards that don't show up on your personal credit reports. The CSR is past 24 months.
@Judique already laid out your options well. You can sign up for the two Amex Marriott cards, which both have elevated 100k Marriott points after $5k MSR in 3 months offers
right now until 4/24/19. The Marriott Bonvoy Brilliant is the high-end card with a $450 AF, but comes with a $300 Marriott credit and Gold Elite status -- will count against your 5/24. The Marriott Bonvoy Business is a business card and won't count against your 5/24, but apply before 3/28/19 to get your first year AF waived, and a lower second year AF.
You should go for the Bonvoy Biz first, because you'll want to apply before 3/28/19, then get started on its $5k MSR. Before the elevated offer ends on the Bonvoy Brilliant on 4/24/19, generate a referral link from the Bonvoy Biz to refer yourself to the Bonvoy Brilliant for another 20k Marriott points referral bonus. This way you're working on only one $5k MSR first with the Biz, then when you're better positioned to tackle the second $5k MSR on the Brilliant you refer yourself for a 20k bonus before the Brilliant's 100k offer goes away. This will net you 220k Marriott points, plus whatever points you earn from your MSR spend. That gets you about halfway there.
Another option, if the redemption math is right, is to buy Marriott points from points .com. Currently, points .com is selling 50k Marriott points for $625. Points .com used to run sales on SPG points before the merger, but I haven't seen any sales for the new Marriott Bonvoy points. This works out to 1.25 cents per point. Again, I don't have the rate you've booked at, but divide the cash rate with the nightly points rate to get an idea what the value of your redemption is, and if that rate is higher than 1.25 cents per point, it might make sense to buy those extra points.
A few things to note: Points typically cover taxes, but not resort fees. And buying points from points .com using a CIP earns 3x UR (or at least did in the last DPs I've seen). Marriott members can purchase or receive as a gift a combined maximum of 50k points per calendar year through points .com, so its utility is somewhat limited. However, it should be possible for "DH" and "DD" to each buy 50k from points .com, and then once those points are in their Marriott accounts, call Marriott to transfer those points to your account. Note that Marriott limits transfers of points between accounts to 100k points per year, they have to call in to request the transfer, and Marriott charges a $10 fee for each transfer unless they have Gold or higher status (your DH's Platinum comes with complimentary Gold Elite status).
Both UR and MR points transfer to Marriott 1000:1000, so you could go that route to top off the points you still need.
I don't know how many UR points you have, so this may not be feasible, but have you looked at what it might cost to book the hotel through your CSR on the UR portal? Even at 3/24 (which is what you'll end up after going for the Bonvoy Brilliant), you can still go for the CIU and CIC for 50k UR SUB each, probably CIP #2 via referral for a net 100k UR bonus. You could also use these Chase Ink SUBs to cover whatever amount of Marriott points you still need.
Hope these ideas help.