I use a duvet cover just on top of my normal duvet and double the pillow cases (on the ones I have at the front for hooking and don't normally use for sleeping). I prefer them to throws as I think it makes it seem more homely and less hooker, plus throws take longer to dry!
I have two sets of these in natural - http://www.very.co.uk/egyptian-cotton-luxury-duvet-cover/490589056.prd?browseToken=%2fq%2fegyptian+cotton&prdToken=/p/prod4552915-sku6939230
which i've had since January, not much more than Primark to be honest, take no time to dry, feel lovely and soft, barely crease (urg, ironing, what's that?) and the only stain is on the corner of one which is bleach!
Thinking of getting these for winter though, just look soooo snuggly! http://www.very.co.uk/flannelette-duvet-cover-set---super-king-size-buy-one-get-one-free/665583237.prd?browseToken=%2fb%2f12982%2fs%2fbestsellers%2c0%2fr%2f100%2fpromo%2f22800045&trail=12981-12982&prdToken=/p/prod5015467-sku7686185