Kris,
Seoraksan requires permits now, and they ask you apply 3-15 days in advance. I posted English translations on a thread under "climbing chat". Technically this applies to Ahgulbawi, too, and permits can be picked up at either ranger station.
Do you have trad gear? If you want trad--
Mureung Valley!! It's not far from Sokcho, and has some stellar cracks, with only the occassional bolt. Heading south, there are some amazing climbs at Yuhaksan (between Waegwan and Daegu). . . heading further South towards Busan there's
Bueongsae for fun long sport. For more remote (read: long approach) but also fun and amazing climbs near Miryang (maybe Dong-il is free during the week?:-)
Sirubong.
If you're heading this way, I have Friday's off, and would be happy to show you
Yongseo,
Horangsan or
Daedunsan.
Can you be more specific about what you want (sport, trad, single or multi-pitch, easy approach or secluded and beautiful)?. . .
How long are you 'round?