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