Post-11g upgrade tasks
There is the standard post-upgrade task list as part of the version-specific Oracle Database Upgrade Guide documentation. The difference between the documentation and the step-ordered approach is that some of these steps can be done in advance. See the following partial list from the Upgrade Guide along with comments:
Update environment variables (Linux and Unix systems only)—from Chapter 2, Maintaining Oracle Standards, only need to edit a configuration file instead of a multitude of scripts.
Upgrade the recovery catalog—already done earlier according to step-ordered approach.
Upgrade Automatic Storage Management (ASM)—step-ordered approach is to upgrade ASM instance (different home) before any databases, keeping it at the same compatible level. After all databases serviced by this ASM are migrated to 11g, then advance the ASM compatible parameter to 11g to enable the new features.
Add new features as appropriate—wait at least a week before changing any database parameters...