I selected the 40k free night - since I wasn't able to get SNAs in time to use for my January Stay.
Not to get off topic....
As for what "40K" can actually be redeemed for... I guess that would be a "peak" Cat 5 instead of 35k? If I get the 3 nights free from Marriott Chase/Amex/Chase Biz - I guess that would give me 4 nights of certificates (could I combine all 4 for a 5th night free?)
May I suggest the JW Marriott Phuket - great property with a great platinum breakfast amenity.