I may not be entirely clear on what you're asking for, but it sounds like a lot of this can already be done with Media Center's task scheduler. When you create a task, you can make it reoccurring and select which days it should reoccur on. Aside from that, if you select a task you've created, you can pause it with the Pause button at the top of the Scheduler dialog. This will prevent it from triggering until you unpause it. Using this, you could also create a daily task to turn lights on but leave it paused until going on vacation.
