Mertzie,
In the Cats Codie Test Kitchen and CATastrophe Preparedness School, I used Pork Spare Ribs. I also bought 4 or 5 beef ribs just to see how they would work... the pork was tastier and more tender. (I don't think tenderer is a word, but it should be when talking about ribs...) I spiced them up a bit with some rib rub, put 1/2 cup water in the crockpot, squirted a bunch of Ray's BBQ sauce over it and covered... I left them on low at least 8 hours. They were tender, falling off the bone kinda good.
Good luck!
Cats