The real problem was I was too cheap to pay the exorbitant prices for proper cable management the first time around. If you shop around for cable tracking, it's somewhere between $7-10 for each 6 foot strip. Plus corner pieces, etc, it would easily cost $100-$150 just for a bunch of plastic.
Well, now it came down to shelling out $125 bucks or living with the cable falling down. So I decided to part with the cash and spend a few hours installing it. I must say, I'm very happy I did--it looks so much better now. In addition to the sticky stripping on the back of the plastic strips, which I'm pretty sure will hold a lot better than the individual square pads, I also screwed in the strips at various key locations into studs in the garage ceiling. That should hold it.