Hmm. For landscape work I don't really like a "blue sky with fluffy clouds", I do however like the quality of light about 3/4 hour either side of sunrise or sunset. For botanical recording photos a high thin overcast is best. Rain or a very strong wind is a deterrent to me; I'd usually carry a compact in those conditions, and very likely wouldn't use it. I think it's just that I find it hard to see "photos" when I'm uncomfortable!

As for poor light - I had the shutter of my Canon EOS 5D open for about 5 minutes in near pitch darkness last night... sky was clear in between showers (all day) and rain moving in (around midnight).