What is the bathroom floor material? What is the width of the wall/kneewall - for some reason it appears in your drawing to be wider than standard 2x4 construction.

My wife is thinking dark gray/almost black tile for the floor. And yes (good eye) the knee walls is double wide/think, so essentially a 2x6. Not exactly sure why it was made like that but the plumbing goes up to the second floor and runs in the middle of the wall, so we’re going to leave it like that.

I agree, but was going to also suggest that the marble continue up the wall beyond the cap of the kneewall in order to also serve to cover the interior tile edge (so a bullnose is not necessary). The other option would be to use double row of bullnose up the wall beyond the kneewall cap, but the difference in material might be jarring. There are some challenges to the configuration that make some of the standards hard to employ in this scenario. We would typically see the floor material used on the front of the curb, but I think with the waterfall of the marble material, I would probably use that marble on the small amount of curb that is left. Much will be determined by what pieces are available in the line of tile that you selected. A really good tile installation professional can help you work through the details - and the devil is in the details on tile.

Lot of good ideas by going up to PHOTOS tab. Select bathroom and then put kneewall in the search bar. Drop down box will appear and select the one that says "kneewall in bathroom". No one of them may do the trick, it may end up being a combination of ideas.

Couldn't get to these photos a minute ago. The first takes the marble down the wall, caps the kneewall and then waterfalls down to the floor. Not your exact layout, but gives an idea.

This is one where the subway is used on top of the kneewall and the front and vanity side are just painted.

Great. Thanks so much you guys! That first picture you showed gives us a good idea of how that would look. Any recommendations on where to get thresholds that are a 2x6 wide? I was planning to do the tiling myself and if I could simply order the thresholds, I may want to install them too, but I feel like I may need something custom. Thanks!

You could have the stone shop fabricate out of the same material that is used for the vanity top assuming that is part of this project. Or ask to see what remnant pieces are available. Those are generally cheaper.

Have you considered eliminating the right angle in the glass by extending the pony wall to the ceiling?