Ideal curtain colour

I would like to go with sheers + block out curtains for all our windows. As they are so expensive and this is our forever house, I would like to choose a "safe" colour that will go with "everything" and that I hopefully won't get sick of. What colour would you recommend? What would you consider to be the ideal curtain colour?

We have not yet purchased any of our furniture :(
Would you recommend against choosing curtains until we've bought all our furniture? The only thing is it could be months and months before we buy all our furniture :(

B