I've been bitten by configuration settings in the past, but now find myself regularly executing sp_configure on unfamiliar servers. The one I haven't drilled into my thick head yet is startup parameters. Startup parameters are relatively harder to find and investigate what they do. I wish startup parameters were more readily visible and self-explanatory like configuration settings.

If I could have one toggle-switch... it would be for an override of Kerberos Windows Authentication double-hop "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'"...argh! I get it, but can you please, just please forward this account?