I should be taking delivery of my new 15" rMBP tomorrow. I believe that the case is solid aluminium? I read the thread about not using palm covers on it, and it started me wondering whether I need to put a cover on anything? Surely the metal case will be pretty hard wearing? Is it wise to put some sort of soft cloth over the keyboard when you close it? I may have other questions about what may need protecting, but at the moment they're unknown unknowns, so any pointers would be welcome.