Best mattress:

Sofitel Bayerpost Munich (SoBed: http://na.soboutique-hotelsathome.com/bed.aspx)

and

Le Royal Meridien Hamburg: Sealy Eden F, sold by the property itself to the public (Sealy mattresses are very difficult to get in Germany whereas you can get them in Australia at every corner and for a fraction of our prices, sort of)

Best linen:

Rocco Forte Villa Kennedy Frankfurt: made by Italian manufacturer Pedersoli (material is linen and feels like air, no source of supply available though Pedersoli is bedding supplier of "Le Meridien Lingotto Art+Tech Turin" as well)

Best duvets, pillows:

Le Royal Meridien Hamburg (and others): made by Muehldorfer, Haidmuehle, Germany (http://www.muehldorfer.com/hotel/referenzen-e.html