The room I’m planning to use for my guests has a concrete floor… As does the rest of my place except where the floor is raised for the den and kitchen. There is hardwood and linoleum at that point.
Debating going with having wall to wall with a 7/16" rubber underlay installed or getting a carpet to fit the room… Wall to wall, almost. The hallway will have a runner to make it easy to clean since the kitchenette is out there.
The underlay will make it warmer and cushier and probably not much more expensive. Lots of places offer to install for free.