Addi or Inox circs only for me!!!
Circs will let you support more of the weight of the shawl on your lap rather than on the needles. Supporting the growing weight on long straight needles can really affect fatigue and lack of skill. Not to mention, you can't ever sit in a chair with arms while you knit because the needles hit them. Scrunching the stitches on a straight needle too much means a stitch can pop of when you least expect it - not a happy event in any kind of fancy pattern.
The coils - the nylon will relax with the shawl's growing weight or a dunking in warmish water or simply hung from something with some weight attached. The nylon stays coiled from being stored in the packaging.
Secondly, different fibers react completely differently on different needle materials. Addis and nickel or teflon-coated (and less expensive) Inox are very slippery. Wool has a lot of little scales (like human hair) that will catch on wood. If you knit tightly (says the voice of experience), bamboo won't let the wool slide at all. If you knit loosely, bamboo can be wonderful. I use wood and bamboos needles only as a last resort because, well, when you have someone like Nancy Bush pick up your work and say she's never known anyone to knit that tightly, well, um, you don't use wood. I had the same thing happen to me in a pine needle basket course. I don't know why I'm wired that way.
Any way, you need to match the material type and your personal knitting tension to the needle material. For instance, if you knit with slippery synthetic ribbon, bamboo can be great.
Do you know about the knitting forum over at www.knitty.com? Those folks are a source for tons of anwers to any question you can think of, plus lots of great patterns.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.