Over time, bias will nearly always win out over straight grain. I've had my own proof of that. I've been making blankets and quilts since the early 90s and those with straight grain and a lot of use have had to have bindings replaced. The bias ones are still going well.
Contrary to the woman at the quilt shop, continuous binding actually uses LESS fabric than straight grain binding. In addition, you don't have to sew all those little strips together - two big strips, then cut, cut, cut. I don't even press it any longer, having learned that it actually goes on better if you DON'T prepress it in half. I must have the instructions in front of me each time I do it since I only make a few bindings a year.
If you are not entering the quilt into a show, use whatever method you prefer. Most show judges will take off for straight grain binding on a bed sized quilt - I don't think they care one way or the other on a wall hanging or miniature. I use straight grain for all my wall hangings and miniatures unless I'm using up leftover bias from other projects. They aren't washed as frequently, so it's not a big deal.
Another reason to use bias is if you are using a striped fabric for the binding. Visually, the angled stripes look much better than straight grain.
Finally, NOBODY is going to beat you up if you choose to use straight grain.
Last edited by IAmCatOwned; 08-06-2012 at 09:41 AM.