The Marriott card is offering 100,000 points right now. Also, if you add an authorized user and they spend on the card, then you get another 5k. The minimum spend is 5k, so you are at least up to 110,000 points in the first 3 months (or more if you spend in bonus categories as I am planning to do).
If I am understanding you correctly, the rooms you are looking at are only $125 a night? That isn't a great use of 90,000 Marriott points. At that point, I would pay out of pocket. I will be using 70,000 SPG points (equivalent of 210,000 Marriott points) for 2 nights hotel, but the hotel stay would have cost $2500 out of pocket.
I accumulate more points for SPG/Marriott by staying at hotels for work. I accumulate points at a pretty decent rate (2-4k SPG points per stay) because they often run promotions that give you double or triple points for a stay. I also opt of housekeeping if I can for additional points (extra 500 per night) and my gold status gives me a welcome bonus (250 SPG points) plus an extra 25% points bonus. It is by far the fastest way to earn. I am staying at a Marriott for 4 nights next week and am excited to see how much I earn from that stay.
You can transfer SPG points from Amex MR, but it is not a 1:1, so the redemption isn't great. You can also spend on the Marriott card, but without using the bonus categories, it is a bad value.