Six hours down the drain... Any way to prevent this in the future besides the obvious?

What Damien said is pretty much what I started doing. Every several minutes while building a lot, I save it to the Library in case CAW crashes (deleting an earlier version so that it doesn't waste space). Also, CAW is more likely to crash if you re-texture every item (if the wait cursor reverts back to the generic Window's cursor, the game is likely to crash soon, so immediately save your lot to the library). The process is actually very annoying, but it beats losing hours of progress and chucking a nearby stapler on your desk at the wall.