How about making a whole bunch of half-square triangle blocks in light and dark fabrics, any size you want, then putting them together to form diagonal stripes? You could make each block 6" finished or even 8" finished. (Does that make sense?)

Kate

Here's a picture that might explain the idea better than I did! It's not my quilt - I just found the picture on Google.

If you used light and dark variations of just a couple colors, it would be even more distinctly diagonal than this scrappy version.

Here is another picture using the same method that Kate described

Here is a link that might be useful: diagonal quilt

Or you could sew strips together and then trim off the top, bottom and sides. This would waste some fabric, but it would be very easy and fast. I couldn't quickly find a picture of what I mean, but I found a picture of a block with this method. Look half way down this link to the first picture of the green and white diagonal striped block and pretend that the scale is much larger and it's a quilt rather than just a block.

Good luck with what ever method you decide on.

Here is a link that might be useful: another diagonal method

I'm with Kate, I was thinking light/dark half square triangles, even before I read her answer.

You could do greens/tans, blues/tans, or any combination as long as the two colors have high contrast.

A very quick and effective layout is the diagonal stripes quilts using the tube strip method. Missouri Quilts and Cozy Quilts both have tutorials on cutting and sewing the tubes. I like this method for quick quilts - it's all in the configuration /layout to make the various looks.