Features such as surround-sound entertainment systems, exotic wood cabinetry and trim, gold-plated bathroom fixtures, hand-woven carpeting and original artwork combine to create rarefied spaces on high. ???Owning your own private plane is far and away one of life???s great indulgences, so people want them done up with style,??? says Eric H. Roth, owner of International Jet Interiors of Ronkonkoma,