I am just embarking on a remodel, so do not have the same experience as many here, but we are considering marble subway tiles with dark gray slate floors that are textured (eg, not too slippery). We are shying away from marble vanity top, because we want the low maintenance/antibacterial advantage of quartz, even though its less "oooh". Our fabricator will do 2 bathroom vanities (36 and 60") in white quartz for about 1200 total (at the same time as the kitchen granite, which is costing a bit more!).

we did 3x6 carrara on the walls and basketweave on the floors. haven't used them yet so can't comment on slip factor, but supposedly the smaller tiles having so many grout lines have greater traction than a larger tile.