A decorative option to cover your walls and ceiling would be to apply tongue and groove material that complements the wood, stain, and/or lacquer that will be on your racking.  You will first need to screw ¾” marine grade plywood on your walls and ceiling so that you will be able to attach your tongue and groove. 

Please  click this  link to view T&G options from WCI:  www.winecellarinnovations.com/res_cus_top_adc8.htm