Why do CEF and GTU carry such a premium over Net Asset Value?
Because this is the premium people are willing to pay for what they perceive to be 'real bullion' versus 'paper bullion.'
GLD tends to have a negative premium because it is a vehicle for traders, and particularly short sellers.
Deviations from NAV in themselves mean little, if the deviation is steady. It is in the fluctuations that information, and opportunities, are discovered.
"Let us then compose ourselves, and bear a firm and courageous heart. Let us feel what we really are,—sinners attempting great things, and succeeding at best only so far as to show that we do attempt them. Let us simply obey God's will, whatever may befall; whether it tend to elate us or to depress us, what is that to us? He can turn all things to our eternal good. He can bless and sanctify even our infirmities." J. H. Newman