Here's my take on this seat mod (done back in 2001).
I'm 6'1" tall and thin so lowering/widening the seat would definitely Not have worked well for me.
I cut down the section where my thighs rested (lower sides of the front half).
Those sections were actually cutting off the circulation in my legs on long rides.
I then added a 1" thick piece of High density foam to the back half of the seat.
I shaped it to blend into the OEM foam and glued it in place to raise myself up slightly and for added padding.
I used a turkey carving knife and rasps and files and sand paper to cut and smooth the foam out.
It took a few hours but I've been very happy with it over the years.
The attached pictures are from Summer 2013, the seat has held up very well and the 1" foam compressed down to about 1/2" in the first year or 2 but has stayed at that thickness ever since.
You can see a slight line where the added foam meets the OEM foam but unless you know to look for it most people can't even tell it's been modified.