My Mac Mini is an always on machine and there’s some apps I always want running, even when I’m not home. Keyboard Maestro makes this happen rather easily. The macro below keeps Mail, OmniFocus and Evernote open. There’s nothing difficult here.
Since the macro checks for the app to be running before doing anything I’m not interrupted if I’m working at the computer, unless of course one of the apps has closed down. In that case I wouldn’t mind the interruption.