Many vendors have certifications with a few different branches, for example Cisco's "Routing and switching", "Security" or "Voice", where you can choose only one as well as a few or all of them. Why not to do something similar?
For example, like this:
Main test, before all of next steps: working IPv6 connection.
IPv6 certified user branch:
Level 1: surf the web via IPv6.
Level 2: IPv6 in URLs knowledge (access testing server by it's address on non-standart port)
Level 3: access some other services via IPv6.
Certified system administrator:
Level 1: IPv6-enabled web server.
Level 2: E-mail server.
Level 3: Reverse zone.
Level 4: DNS servers.
Maybe FTP server too.
Certified network administrator:
Level 1: IPv6 subnet behind a router.
Level 2: IPv6 firewall
Level 3: RIPng
Level 4: OSPFv3
Level 5: BGP peering (using private AS numbers)
Automated tests for this branch are not so simple to implement, but I think they are useful and funny.