A firmness label isn't a measurement.
An American “firm” often feels closer to a European “medium” to me. In Europe and Asia I've found more supportive beds, especially Slumberland beds and other higher-end hotel models. They give a little at the shoulder but hold their shape under my hips. That is what I mean by comfortable, not a mattress that just feels soft when I sit on it.
Most North American hotel beds I've tried are too soft. It feels as if every one has a three-inch pillow top, including some Sealy beds. That padding feels luxurious for ten minutes, then my hips sink all night and I wake up with a sore back. I'm tired of hotels treating that first soft impression as comfort.
Support should be standard.
Park Hyatt and a few higher-end Hilton properties have usually been the North American exceptions for me. I've slept better on a simple rollaway than on a mattress worn into a hollow by a thousand guests. I should not have to hunt for a bed that supports my back at a luxury hotel.