OmniOS will run just fine on recent VMware products, with a few caveats.
Follow the directions for installing VMware Tools in a Solaris guest
If running the text installer from the Installation#FromCDisoISO, the guest must have a virtual floppy device configured or it will hang during installation. Either add the device via the VMware GUI or add the following to your .vmx file:
floppy0.fileType = "file" floppy0.fileName = "path_to_/floppy_image/Omni.flp" floppy0.clientDevice = "FALSE" floppy0.startConnected = "FALSE"
The floppy image can be an empty file, but it must exist. If the floppy is the default boot device (which is the case if you add it through the VMware GUI), your VM will boot into Pong - (see http://communities.vmware.com/message/1454298).
The r151002w ISO, which contains text-installer fixes for device detection under VMware, is required. These fixes were previously only available in “bloody”.
As of r151004, this is no longer an issue in either stable or bloody.