From a Commenter on my posting at groups.google.com:

 

After reading Sheldon brown's thoughts on this over and over, I went
out and found myself an old but useable Selle Italia Flite.  It's stiff
and hard, but after getting over the minor saddle soreness, I found it
so much easier to ride on then the big, bouncy gel thing I was using
before.  And, my circulation in my crotch isn't cut off, which it was
before.

 

I'd say that you should look for something that's not all cushiony.
Sounds odd, but if you feel your sit bones (in the lower end of your
butt, BEHIND your groin) getting sore, then that's a good sign.  If you
feel any numbness below, you either have a bad saddle, or it's adjusted
poorly.  A lot of people adjust their saddles so they're tilted, and I
think this is a bad idea.  I had a saddle that was only a couple of
degrees forward, and I was getting sore wrists and palms, and losing
some feeling in my crotch.  I also actually think that the harder the
saddle is, the quicker you get over the initial soreness.  In the past,
I'd be in incredible discomfort from saddle soreness, but now, I barely
feel anything like it when I haven't ridden for a while.

 

You'd be surprised at how small and hard the thing can be, as long as
it supports you at those bony contact points, rather than in the soft
tissue between your legs.

 

I'd really recommend trying out one of the classic Italian saddles
(Selle Royale, Selle Italia, Selle San Marco, Vettas are nice, too), or
a Brooks, if you want to drop the dough.  They're all a bit pricey, but
I'd take a beat up, used one of these than a brand new
gel-comfot-plush-thing-a-majig-seat anyday.