Drew Dalgleish wrote:
I'd go unfinished for slip resistance. How hard would it be to remove
it once in a while and pressure wash any accumilated crud?

Dashew's "Cruising Encyclopedia" made a good point. In a grate there
are many holes you can only clean out with a toothbrush. Tedious.
Their suggestion was to make a 'grate' but with all the pieces going in
the same direction, (held together with a couple cross-pieces on the
back). Much easier to clean out.