Carpet color

Have you thought about maybe repainting the walls? I guess if you're worried about marks, i'd go with a beige kind of colour on the floors or something a little darker! You could also just go with a stain retardant carpet - here in Australia there are now heaps of brands that make carpets that wont hold stains, if you wipe them up there's no trace anything was even dropped! Do you really want carpet? What about linoleum or timber flooring, maybe tiles or slate? - then there's no staining problem but you can make it look cosier with a big rug - i like the 'shag rugs' myself coz they're thick & fluffy! Good luck!