I use iterm2's "badging" to set a large text badge on the terminal of the name of the system as part of my SSH-into-ec2-systems alias:

    i2-badge ()
    {
      printf "\e]1337;SetBadgeFormat=%s\a" $(echo -n "$1" | base64)
    }

It's not quite as good as having a separate terminal theme, but then I haven't been able to use that feature properly. :(