Gabe,
I really like the ideas expressed here. and the way you seem to be responding to user input so I figured I would add mine..
Since you are hinting at the "adaptability" of the cooler why not include both stickers with the blocks and also make the template available on your website so owners could make their own custom graphics and apply them.
The level of personalization is endless that way. I know your printing cost would go up alot but perhaps the increase in volume would offset that.
I also think a stainless plate option or other inlays could be a nice option for customising.

BTW: I own 2 6970s and will be buying blocks so I do speak as a potential customer, Most of my liquid gear is your stuff anyway!!