Here is a play on the grand staff. It uses six lines with dashed 'C' lines. It is actually a repeating three line layout. It doesn't use much more space than the standard staff, but I think it has improved visual separation. Notice that 'B' floats, which is the only extra space used. The blank space between staffs isn't accurate. It is just there to show space for ledgers. Ledger lines would follow the same pattern using a dashed line for 'C'.
https://i.imgur.com/qPdbZqs.png