By default VMware Fusion suspends a Virtual Machine that is not explicitly shutdown from within the Guest OS, i.e. when closing the VMware Fusion.app while a Virtual Machine is running or clicking the close button on the Virtual Machine's display window. This behavior can be changed in VMware Fusion's General Preferences and when doing so it writes the following to the "/Users/${USER}/Library/Preferences/VMware Fusion/preferences" file.
pref.vmplayer.exit.vmAction = "poweroff"
Yes, VMware Fusion uses "vmplayer" in this preference and the file is User Specific not Global. Nor do I know if this can be set globally however a login script could make sure that setting existed when each User logs in.
The other option is to set the following in the target Virtual Machine's .vmx configuration file.
suspend.disabled = "TRUE"