Skirts are great, but a dress is even better - a stretchy jersey A line one. A dress is cooler than trousers, it doesn't chafe around the waist, or get rucked up with my backpack's waist belt. Just did 4 days hiking through the Pyrenees in August, seriously rocky, lots of scrambling, up and down, and the dress gave me the freedom of movement I needed. It was 30deg C (85+ F), and the dress was cool, with air flow. The below-knee length, coupled with boots and hiking socks meant I didn't have much skin at risk of sunburn. Who would ever bother with shorts or trousers?