For .. well I guess years now, I've fought this setup. And what is crazy is that the main article I follow has always gotten me 99% of the way there.
http://wiki.xen.org/wiki/Fedora_Host_Installation
But at some point the virt-manager stopped working and I started using either older host versions (think Fedora 18 was the last easy version, and Fedora 20 I got it working somehow)
Anyway, the salient thing is that after following those install instructions above, that if you enable and start the libvirtd services (for some reason the install doesn't enable them) then virt-manager will start up.
systemctl enable libvirtd.service
systemctl enable libvirt-guests.service
and then the starts too.
Hopefully this holds true for a few more years.
Also, for grub2 boot not seeming to get set, found this gem:
(This) method fails to work on some F20 systems and later due to a missing or improperly linked /boot/grub2/grubenv file. The /boot/grub2/grubenv is symbolic linked to /boot/efi/EFI/fedora/grubenv but /boot is not mounted at the time of booting. So grub2 does not have access to the environment variables. To fix this, change /boot/grub2/grubenv to point to ../efi/EFI/fedora/grubenv instead and your chosen default OS will boot without any problems.