This is not rocket science as there is an easy to find solution at http://communities.vmware.com/message/1602618. This changed from previous versions of vSphere where I think the option was in the VM. Makes much more sense now. I assume (because I have only got one host) that in a cluster of ESXi hosts all guests would be shown and the ones specified for power-on would be powered on on *this* host.

The online help for this topic says:

1 Display the virtual machine’s host in the inventory.

as the first line but I am not too sure what it means by “the virtual machine’s host” (if it does not have one).

For the record, my own picture is:

And I will try an experiment with multiple hosts in the office lab tomorrow.