I have found, during my work with massively complex system environments, that there are a few top issues that can affect configuration management. Here are some of them:
Set the explicit disk to use when installing via JumpStart server.
Check for all patches!
Read all of the release notes.
May need to access to a 10.0.0 network for the Sun StorEdge network FC switch's initial configuration.
When using Fibre channel: be aware of hard address vs. boxid vs. target id.
When using the Sun StorEdge network FC switch, do not forget to "apply" the changes that were made, as necessary.
Set port types on SAN switches before making zones.
Use ports 1, 4, 8 .. to connect to Servers, if possible, for better performance under some conditions.
Be sure to check the /etc/system file. Do not blindly roll things forward, e.g. priority paging.