Guild Shields are fun!
Unfortunately, most of us don’t have access to that aspect of the Guild interface.
I think it would be really fun for everyone in the Guild to be able to play with the Guild Shield, though only the highest-ranked players would be able to commit the changes.
The best part of this is that everyone could make suggestions for improvements by screen-shotting their creations.
I can also think of an alternative option, inspired by someone who released a web-based character creator to build hype for a game before its release (was it Dragon Age?).
A web-based Guild Shield Builder would be really fun, and achieve the same thing. Even better, the Shields could be shared using codes or something. Lots of options here!
I know it doesn’t feel very commercial, but it could really build excitement.
Anyway, that’s my idea.