On my first quilt I used the Clearview ruler and thought that was really great. However since I've made more quilts with this pattern, I've discovered that a rectangular ruler with a 60 degree line is more useful, combined with a paper template that will be shipped with the pattern. I don't use the Clearview or other specialty rulers anymore.
I use two sizes - 6x12 for when the blocks are still relatively small, and then I switch to the 8.5x24 when the blocks get larger. It would be much nicer if I could find a ruler that's about 15x15, or even 12x12 with the 60 degree line markings, but none of mine are like that.