It's not the selle- it's the Prologo Kappa Pas on the Caad9-4. I'm now at about 150 miles on it (and I ride regularly, so it's not just regular sore-ass - I know what that feels like ), and I think the problem is that the anatomical cutout is just not a good fit for me.

I was professionally fit, and also checked the saddle-bb measurement against my old bike (which I loved), and they're just about dead nuts. I spent some time poking around yesterday and my old vetta saddle looks very similar (I know looks are decieving, but it's a place to start) to the Fizik Antares, so I'll go by the shop and see if they'll let me demo one of those.

Thanks again for all your help!