[necromancy- didn't want to create yet another threatd about beds]
Now, this is just my way of thinking at work again, probably, but I hope it's a decent idea.
I'd like to see an assortment of beds, bed-like objects, and bedding. For example...
A new designation, 'carve rough stone bed' could be added (...Perhaps even rough stone furniture in general, but that might make things a tad easy.), prompting the miners to take an unmined (rock) square and carve it into an extremely rough facsimile of a bed.
Now, obviously, this would be extremely uncomfortable, maybe better than sleeping on the floor. Smoothing it could make it a bit better to sleep on.
Some form of bedding (Pig tails stuffed into a roughly matress-shaped cloth) could then be placed on top of it for a bed that's... passable. It still wouldn't be as good as a bed with a wooden base, I'd imagine, but at least your dwarves would have a place to sleep.
I've also heard about hammocks. These could be helpful too, but again, we presumably want to retain wood as the most important/best bed material.
Perhaps with a little thought, Animal Trainers could be used for hammocks, given a tame, intelligent variety of large spider...
Bedding could include a simple mattress, hay or a hay-like plant arranged in a large pile, or something similar (a pile of cloth or leather?)
Perhaps, in an emergency, something could be done to the floor itself to encourage comfort. A carpet or something.
I'm all for wood remaining important to dwarven happiness though... but it's midnight. Maybe I'll think of something to add later.
[/Necromancy]