TVpierce,
I have the same problem on the blacktop when using the regular jack and stands. Really chewed up the upper part of the driveway. I'm kind of planning to have the upper section of d-way cut out and than I'll have a nice concrete slab poured (all a big maybe). Gotta do something about getting the cars in the air though, I'm ok working underneath, I just can't get back up :-)