I like virtualized Solaris guests from a Solaris 11 host with no desktop (GUI) installed.
For RDP access so guest console is accessible:
$ VBoxHeadless --startvm vm1 &
For no console access (generally not a good idea, unless security constrains mandate):
$ VBoxHeadless --startvm vm1 --vrde off &
Alternatively, on more recent versions of VirtualBox you may be more attracted to the VirtualBox VM autostart feature, which saves us typing the above commands for the VMs used every time the host system is booted.
