Another good GIAC training is the GIAC Incident Handling ( GCIH 504 ).
For the rest, I would say it depends on the type of logs you are collecting. For instance, if you collect logs from specific application like IIS or Oracle, having a good knowledge of HTTP and DB would help your analyst to better understand the risks related to the alerts they get. However this type of training should focus on the security aspect ( no need to be a web developper or a DBA to understand risks related to these applications ).
Depending on the role of your analysts, especially if they develop some AS content, it could also be interesting to have some basic knowledge in scripting and regex.
I can't believe I missed a plug for the ArcSight User Conference! Good work, Joe.
I like GCA's advice as well. GCIH is just a darn good cert to have regardless, the tech-specific training is really critical for folks that'll be touching security devices or systems, and the scripting / regex stuff is great for SIEM hacking.
I always found job rotation or job shadowing to be useful.
It's good to jump on opportunities to do new things. When I was offered firewall work, I took it, DBA work, I took it, forensic work, I took it.
The more jobs you learn, the easier it is to understand the events you're seeing on the SIM.