Aside from claustrophobes, this might work alright. But it would require a lot of material, and it would have to look good, because people like beds that are made out of nice looking wood. And it's expensive building a roomy king-size coffin out of maple ;)
Well it wouldn't be claustrophobic assuming you make the dome with sufficient headroom. You could do some human factor studies and determine what size of enclosure people can lay down inside and still feel fine.
In terms of material, I'd prefer something more techie than wood - some sort of composite material to make the canopy light and moder looking. Maybe like a large oval shape.
