Hey Brendan,
If you are using CSD, then you'll find information regarding the log files at this link:
http://www.cisco.com/en/US/docs/security/csd/csd35/configuration/guide/CSDglobe.html#wp1208960
If you looking only for client files then on a MAC they are located in /Applications/Cisco AnyConnect VPN Client/Contents/Resources.
However particularly for crashes you can follow the following steps:
- Open the /Applications/Utility folder and launch the "Console" application.
- Select the "Show Log List" option.
- Navigate to "LOG FILES -> ~/Library/Logs -> CrashReporter"
- Look for any "Cisco Anyconnect" or "vpnagentd" logs ie:
~/Library/Logs/CrashReporter/Cisco AnyConnect VPN Client.crash.log
Hope that helps.
Atri.