I found a thread from 2010 where the poster asked if someone can check into a Marriott property if the reservation is in their spouse's name. Most people said this is possible if both spouse's names are on the reservation. Is this still true?

yes, do so quite often based on where my wife and I are traveling where we meet in a location.

We have done this many times, though my wife is usually only checking in a few minutes before me while I park the car. As long as your last names are the same and your spouse has the same credit card, you should be fine. We have also done it at IHG hotels with no problem.

--Jon

Disclaimer my experience is with US properties. International properties, especially Europe and Asia may be different.

I've done this without issue, last time was in Geneva. As always, it's wise to preemptively reach out to the hotel and notify them of the situation.

Add spouse's name to reservation. Works like a charm.

David

Add unrelated friend's name to reservation (different last name)

They were able to check-in before I arrived

It's usually fine if the second guest is listed on the reservation.

Despite what others might say based on having tried it once or twice, it is NOT 100% guaranteed to be OK at every hotel.

In the US the requirement for all of the chains is supposed to be that they have to have permission from the person whose name is on the reservation to let you check in. Usually this is in the form of putting their name in the also travelling with field or similar. I usually work in the summers as an umpire for softball tournaments, when I travel, the Tournament Director is responsible for setting up the hotel rooms. Every time they have not allowed me to check in until I knew whose name the room was under and verified that either my name is listed in there somewhere or verified by voice that I was allowed to check in.

Have done that many times. With family members (eg. parent, brother) but also with friends with surnames different than mine.
What I do is contact the hotel in advance and ask them to enter a comment to my booking saying that XXX person will check-in on my behalf as I am arriving late.
I also make sure the first person checking in has the reservation confirmation email.

The hotel might ask the credit card of the first person arriving to the hotel, but when that happened, it was easy to change the credit card for mine once I arrived.

Even though I frequently forget to do it, I agree with the recommendation of adding your spouse's name to the reservation to prevent potential issues. If it is someone other than an immediate family member you're sharing the room with, then it becomes critical to explicitly add their name to the reservation to avoid problems at check-in.

The only time I call in advance is a slightly different scenario. I have booked multiple rooms for my extended family when we're traveling as a group (paid and/or award stay). I will call either MR or the hotel to change the names on the reservations over to the intended guest. Sometimes I have been able to change the names online via the web. It has been a few years since I last did this type of booking, so I don't know if the current incantation of the MR website will let you change the names online. When in doubt, call the property in advance for this scenario.

--Jon

There are several additional reasons for making sure that all room occupants are listed on the reservation: If the person is locked out of the room, the front desk should check photo ID and verify it against the name on reservation before issuing a new key card. It could cause trouble with room charges in the restaurant, etc. Finally, in case of emergency, it's better if the hotel knows who is supposed to be staying in the room.

YMMV. I have had issues w/ this. Even had a note in the reservation about it. Hotel did not let her check in till I arrived late at night. Agreed that almost always this is no issue, but YMMV.

Added second name in reservation. No issue at all with Ritz Carlton in Tokyo (December 2019).

We've done this numerous times, we don't have the same last name and sometimes she won't use the same card on the reservation. It's never been a problem in the US and abroad, but I've always called the property ahead of time and added her name to the reservation.

One thing that I find inconvenient is that there is no way to add a name during the booking process if you are doing it on the website. Requires a call to either Marriott or the hotel.