Circadian Daylight has a brightness-throughout-the-day option that you might be interested in. It applies changes when a dimmer/bulb gets reported as powered on. Very smooth transitions, too. I have an option in there for custom max/min brightness, too, but it's not wired up yet. I should get around to that this weekend...
For rule machine, I'm not sure I'd have a cleaner solution aside from using a capture-restore (power-state only) rule to determine that state prior to sending the command.
