Jon,
As you said, the reality is what they actually sell for, not what anyone believes and if 1997's consistantly sell for more than 1996's, I'm with you.
The part I don't understand is the perception that there were improvements in the 1997 GTS that the 1996 GTS's didn't incorporate over their early life. For example, 1996's GTS had several areas for oil leaks. Some had oil pan issues and some had timing cover gasket problems. 11 years later, I've got to believe that all of them were fixed and 99% of that under warranty. So are 1996 GTS still oil leakers? I doubt it. 1997 GTS's had bad intake manifold gaskets versus 1996 GTS's. They leaked. Do 10 year old 1997 GTS's still have bad intake gaskets? I doubt it.
The facts are nothing about the 1996 GTS except the cast wheels and the stripes are different than late 1997 GTS's. Early 1997's even had the same cast wheels as 1996's. Both had cast iron exhaust manifolds, both had dual airbags, both didn't have an alarm override, both had the same sound system, both had 17" wheels, etc. It's not like the 1997's had ABS, power mirrors, 18" wheels, power trunk release and 10 more horsepower vs. the 1996's.
Anyway, though I believe long term the '96 will carry a slight premium over the '97 it doesn't matter as I'm not selling.