I simply decided to play it safe, and e-mailed the concierge to book my upcoming stay. Frankly, given how the Citi travel site kept erroring out, I doubt booking online is much faster than shooting an e-mail to the concierge. :D

TPG has added the following:

Any idea how we could tell which stays booked online are eligible for points and benefits? Seems incredibly vague.

I would interpret that as none of the stays booked online are eligible for points and benefits. Much discussion when this "benefit" was announced that this would happen. The Citi Online Advertising Agency (aka The Points Guy) assured everyone that it wouldn't be a problem....sounds like he's backpedaling fast now.

Sounds like a reason to just continue booking via the Concierge.

I booked my first 4th night free reservation this week and was impressed how easy it was, and that they were able to book me at the Hilton discount member rate.

Property specific.

Agreed. The agent I spoke to recently was very pleasant and efficient. Not sure if I just got lucky but the concierge seems a lot better than it was a year or two ago.

So far, I have had quite a bit of luck when it comes to booking through Citi Concierge. All the phone agents I have spoken with were all very competent. I have had no issues so far booking 4th night free with corporate rate, conference rate, etc.

In a few occasions, the agents were also able to complete hotel best rate guarantee claims on my behalf (with my instructions). So far so good! ^

Agreed! Calling Citi Concierge (in the wiki above) result in better rates than those shown on the Citi TYP website, offers the ability to loyalty account information, in addition to special rates, as stated above. When calling the number on the card, be sure to be connected to Citi Concierge, as the standard TYP reservation agents appear to be limited to the website information.

It's a bit sad that competency is such a pleasant surprise, but I'll take it nonetheless.

Since the program revamp, has anyone had any luck getting a post-paid booking made with the 4th Night Free?

When I query my hotel, it shows only the prepaid rate online - with me paying Citi's travel agent directly. The hotel also has a regular (no deposit, 24-hour cancel) rate available. I want to book that, pay the hotel, and receive my refund later, as it was under the former system.

Anyone know if this is still possible via the email route? (e.g., *not* using the online portal)

I have made post paid rate booking after the change (took advantage of 4th night free in the hotel itself). It was done via e-mail + phone to follow-up, although I assume just regular post-paid rate will be processed quickly via e-mail.

Perfect: I'm going to submit such a request today. Thanks!

Just tried the new booking portal for the first time and I actually found an African Safari Lodge that is eligible for the 4th night free. ^^

Marina Bay Sands Rate?
 

I am thinking of getting the Citi Prestige Card for the 4th night benefit. I am probably going to wait until the end of the year to apply. I wish there was a way to check available rates. I just want to make sure it is going to be worth it. Is someone with the card willing to check the available rates for Marina Bay Sands in Singapore from 1/11/18 and check out on 1/16/18.

I am am interested in a premier room base rate or the city view rate. Anybody willing to help me out? I figure if I can get the fourth night free it will pay for itself with this booking.

Premier King $495 from the website. In my experience, it would be very easy to call in and request a quote. If necessary, describe where you found your preferred rate. This should be a no brainer. I have used it probably a half dozen times in last two years.
Also, if you apply in time, you can receive your airfare credit for 2017. Cheers.