I have Brooks B66 Champion (twin saddle rails) and the more recent B67 flyer (normal saddle rails). The B67 has slightly less "give", but still useful compared to unsprung saddles.
These are on bikes with flat bars, with these I tend to use a slightly more upright riding position, they are also on the bikes I tend to use most off-road. I use B17 saddles without springs on my bikes with drop bars.
All these saddles have more or less the same width and length of top, which seems to suit me best. I've tried narrower saddles and don't find them very comfortable. Not yet tried wider, but might as I get older.
Note that the B66 standard is wider, this might make it better for an even more upright position.