If the stay is 3+ nights, isn't it triple points for the promoi?

13,500 - Base points
13,500x2 - Promo points
3,375 - Gold bonus
43,875?

I take it you don't have a card? On my aspire card (free diamond) the multiplier with the triple points promo is x 54 per dollar, so it would yield 72,900.

If it were me and I would earn 73K points, (that's almost worth a free night at a nice place) In a heartbeat I'd pay the cash, as I frequently redeem 90K for properties at can fetch $700+ per night.

If you don't have the card and the points are 43K, I'd personally make the decision around whether you want to spend 4 nights or 5 in Chicago.

If you were staying at a beach resort and the 5th day would be an extra day of vacation on the beach, 10,000% take the extra night. But if it's Chicago, I love Chicago but is there enough to do for 5 nights? You'd have to consider the extra day of parking, food, etc. in the equation as well.