We do have white wooden venetian blinds and at the moment and floor length (actually longer but unless they are made to measure just get standard 229cm for floor length).
I've ordered new curtains and have tried them, these are just to the window sill. I'm not sure if i like them or not! Because they aren't going to be 'used' and just there for 'decoration' I don't want to spend a lot but I don't want just plain cotton, I've found out from before that curtains in our lounge need to have texture. My old ones are a natural colour textured weave and these new ones are like a pale pink, silk textured but look almost velvet/suede. We have one navy painted wall, the others are white and a beige fabric sofa. The pink does look well with the navy wall and beige sofa but I just have a little niggle, are pink curtains for kids bedrooms? Maybe the longer length may be better .