Pretty massive thread dig here, but I impressed myself today by finding a perfect bag for my Press 23 and had to report back.
My solution is a 16 can soft cooler. Its padded top, bottom and sides, has a flip top lid, has some mesh pocket action inside, an adjustable sash with padded bit for the shoulder. As required, it fits the press with handle on and 100mm lens (retracted for a bit more wiggle room), ground glass back, spare back and yes, I think I'd get at least one more lens in there too. I looked at Coleman and it was a bit bigger than I wanted, so got another brand which is a great fit.
Added bonus is that it can sit in the car and not get too hot for a few hours
These things are pretty tough too, most have ripstop nylon fabric top and sides, and mine at least has a cordura base... its pretty hard to beat!
$20.