I use wood shavings because it's easy to clean out, antiseptic qualities and hay or straw can carry fungi and mould spores when damp and can affect the eggs (in some way can't remember), so I never use straw or hay.
I read your post just as my neighbor was raking up huge piles of dried pine needles. I grabbed a bunch and threw them into my run. I am thinking of grabbing some more and doing a deep litter thing for the winter. I live in Michigan, so we are probably going to get some snow this winter. i know you don't, but I am guessing you deal with rain. How do the needles hold up in longer periods of damp?