I've done Gwanaksan as a newbie and it is ok. It's really accessible via subway. I can climb on weekdays until around 1 or so on weekdays and I can start as early as you want. If you want some nice pics of death triangles then this is the place. I live in Pyeongchon, Anyang-Si.
"You have lost much poundage."
Grace Chen(Former co-worker in Taiwan)