Go with black. We just took back a shiny silver shower door that had black gasket material between the shiny silver and the white shower.

If you only use liquid soap to bathe with, it should reduce or eliminate the soap scum problem.

1. Some hardware will need to be attached to the white walls. I'd rather have silver hardware attached to the white walls than black, so I'd prefer silver hardware everywhere.

2. Are U-channels needed? Can you use minimalist wall brackets like those shown here (I know this isn't a three-sided glass shower) to support the glass walls instead of U-channels?

--amateur

Lawrence Sprowls-Hi-thanks for the comment. That design uses 2 support arms and with a 3 sided shower would probably need even more than 2 support arms. I prefer a cleaner look.