For the baseboard we're considering a couple options. Either a plain rectangular board. A small bead detail around the top of the baseboards to give it a little interesting detail and help keep from having a big ledge for dust to gather on (not the most authentic trim but still fits with the style). Or a more complicated baseboard like this with a slight miter on the top and a rounded cap part way down:
DIY Modern Craftsman Window Trim
Tutorial for creating modern craftsman window trim. I love the clean crisp look of the white craftsman trim in this powder room!