It really does make me feel better knowing I'm not the only one whose child is entertained by giving their mothers heart attacks ;D
And, thanks for all of the tips you had for trying to remove "art" from the walls! Anytime I'd get a new tip I'd run over to give it a shot.
Here's a little run down on what I tried - what worked and what didn't - in case you run into this in the future.
Something to keep in mind is that I used flat paint in my living room, which I'm sure makes a difference when trying to remove permanent marker.
Magic Eraser
Took off the marker... AND the paint :(
(I did use it on my semi-gloss trim and cabinets and any scuffs came off beautifully. I'll definintely use this bad boy in the future for those)
Rubbing Alcohol
Similar result to the Magic Eraser - took off the marker and the paint
Baking Soda & Water Paste
Unfortunately did nothing :(
WD-40
Took off some of the marker and a little bit of paint. It did leave behind a greasy mark, which probably wouldn't have been that noticable had it not been on flat paint.
So, the only solution ended up being...
Primer and Paint.
The takeaway from all of this, since it's probably frowned upon to tie your children's hands behind their backs when you need to step away from the room (I kid, I kid - no need to alert the authorities!), is to make sure you have some leftover paint for touchups. Or, make sure you save the color formula label from the paint can so you can easily have more remixed if needed.
I actually think I broke Izzy's heart by painting over her masterpiece. She was a little bummed when she walked over and saw it wasn't there the next morning. Is it weird that I feel bad about that?!