Vacation on South Korea

[jd123131]

I plan to visit SK in Winter for a vacation(u know Seoul, Jeju island etc.). Last year I had been to Maui, Hawaii and this year I would like to expand my horizon(international) by visiting SK. If any college students have ever been there I would like to hear from you about how much would a trip like this cost including stay etc., what did you specifically do in SK, and how long is the idle time we need to truly enjoy SK!!

P.S. Also very important, I would appreciate if someone could tell me if this is an idle vacation place and is it worth it and when in your opinion is the best time of the year to visit SK.