Thomas Covenant was an adult in a Wonderland, and so was Louis Wu.

I think the trick is to make the Wonderland frickin awesome so the jaded adventurer feels lost and must reset his pattern of thinking, or to make the protagonists tourists who expect different but are surprised by something that reminds them of home.

An example:
I once had an elf child interrupt a meeting between the PCs and his mother because he skinned his knee. How many times have you seen kids use some pretext to involve themselves in adult business? The players started asking questions about the dangerous forest and how children survived, and figured out the forest was only dangerous to them because they blundered blindly through monsters' established territories. The adventtre went from a series of encounters to a vacation in elfland.