Override default settings for single session

I would love to be able to override default settings for a single session. For example, I would like to be able to turn on the feature to automatically lock the screen when I disconnect. But if the user is at their desk, I'd rather not make the screen lock on them when they're just gonna turn around and unlock it again. Another example is the desktop background image. I like to leave it on because in the past people have complained about the images not always coming back on right. But if I'm having performance issues with the screen refresh rate, I'd like to be able to tell it to take out the desktop background for the single session.