If you need larger pieces, say for a back, you can straighten it in sections. I bought a bunch of yardage from a quilt shop that was closing and managed to straighten it and ruler fold it by doing it in sections without cutting. Most of what I got was still on the bolt, so you know how large those pieces were.

Sorry for the stupid question, but once you get it straight, do you cut along the salvage or against it, or does it matter?

this has been a great thread... I've always wondered this, but didn't ask... Thanks everyone!!

If I am cutting borders and binding I cut with the length of the fabric when I have that much length. If I am cutting strips for piecing I cut across the fabric. The crosswise has a smidgeon more give than the lengthwise, so I prefer it for easing patches/blocks together. If you cut your borders from the crosswise you will almost always end up needing to piece them.