Hmm.. I can't really add too much more than what's been said here already. I used to ride a motorcycle (and FI used to race motorcycles).
I'm a huge gear nazi. I always wore jeans, gloves, jacket, helmet and boots and when it was too cold for jeans I had a heavy textile material pant and jacket as well as riding leathers.
I see too many girls on the back of bikes in shorts and flip flops and I can't stand it. I know it's their choice but they won't be too happy when they have road rash all over their bodies.. or worse!