I think a nice feature would be the option to show unavailable ticket options to non registered users. Currently, when this option is enabled, only logged-in users get the "N/A" in the booking form.
I've come up with a temporary fix for this by changing line 190 in em-ticket.php from :
$condition_4 = !$this->ticket_members || ($this->ticket_members && is_user_logged_in());
$condition_4 = true;
However, integrating this in the plugin options would be a much appreciated feature.