A note on the PC hardware front:

Solaris 11+ has been doing very well for me on PC-based platforms for quite a few years now. The drivers handle everything up to probably the lastest-gen( minus 1) LSI or Emulex or any other disk/fiber controllers, 10Gbe Intel or Mellanox ethernet cards, and generally support enough USB stuff to make it worthwhile for me - USB serial port adapters actually DO wind up in /dev/cua ;)

The Intel processor support has been great w/NUMA aware scheduler (check out lgrpinfo on a Solaris box) which is very useful for Oracle DB, and a few other things I can't think of right now.

I don't use it for desktop though, except for Xvnc with a bunch of xterms open so I don't lose my mind when my Windows workstation gets more perpetual updates and I have to reboot it. Xvnc also helps to deal with the inevitable Oracle GUI-based installations.