would be over several floors, packed floor to ceiling with yarn and have little ladders on rails so you could root around in the top shelves.
it would have a whole range from really cheap to ultra expensive and would have every colour conceivable so that you could actually buy several matching yarns in the same brand for eg. cath kidston rip-offs or knit a kaffe fassett jersey using the colours he suggests.
it would have a tea shop at the back where you could scour mags and patterns for your next project whilst sipping piping hot tea and gobbling gateaux.
it would have directories of yarn according to washing instructions (i'm sick of finding gorgeous wool for my dd only to find it has to be hand washed at half moon while the wind is blowing from the north east and dried flat in a room with bouquets of lavender and an ambient temp of 12 deg), and listings of which yarn is appropriate for a needle size.
it would be open late a couple of nights a week for knitting groups or just to finish ufo's.
would you shop there?
what would your ideal be?