I have most my stalls w solid partions, but I do have a few w just bars, so horses can see each other,
It works well for horses that get upset if they can't see another horse, or weaning a foal from mom.
So if you could have both would be benificial.
Ours are steel as well, never had issues w rust.
A bathroom is a huge bonus for any barn, a good sized tackroom, and I also think a feed room is a huge asset, it keeps feed secure from horses, rodents, and keeps barn looking much tidier.