Thanks everyone for the feedback. My question wasn't really whether the Retina is better (I know it is), it is whether its "betterness" is more pronounced in the Apple Store than it is under dimmer lighting. My theory is that the Retina's superior glare control makes the margin between the two panels even more pronounced in a place like the Apple Store with all the ambient light.
I actually find that the difference between the retina and regular panels is LESS pronounced at the Apple stores when the screens are jacked up to full brightness. I can't explain why, and it may be subjective on my part.