i went there last october autumn. backpack with frens.
if you wan to enjoy and see lots of things , u can go to busan.
over there, u can see their fish market n eat raw seafood (yummy).
and many more.
u can oso take bus from busan to gimhae (30mins). gimhae has alot of interesting places.
other interesting places: sorak mountain, gyeong-ju.

je-ju island is worth for visiting but the bad thing is u need to depend the weather of that island. if the weather good, u can get to visit many places at there.
there has one kind of fish only live nearby je-ju island ocean. you can enjoy it there! (forget wat's the name of the fish).
btw, u need a flight to jeju island(i heard approximately 3-4 hours from seoul(incheon airport)).

u need adaptor cuz they are using 2 pins plug.
expenses: not sure depends on ur shopping expense. but their food is quite expensive.
transportation for bus cheap and convinient.
transportation for KTX(train) expensive
transportation for LRT price ok.
water : u can get anywhere for free mineral water.

nami island is where winter sonata filming place - u need around 2 hours to finish walking the very small island.

seoul - i think tour guide might bring u to world cup stadium, "artificial river" , shopping places, "south,east,west or north" gates, nampodong (cultural street) , korea castle. they have one place for shopping like petaling street (price very cheap).

sorak mountain - they have 2 types of way to go up.
if u r rush , u can take cable car. if u have 2 days-3 days, u can climb to sorak mt.

incheon - u can enjoy raw seafood if ur tour guide brings u there la... very yummy!

busan - jagalchi fish market(raw seafood) , dalmaji hill, haeyong dae beach(very nice beach) , n shopping much cheaper than seoul. n many places more.

gyeongju - u will be going to king tomb, half moon park, n one hill there has many temples . peaceful city (more to traditional place)

daegu and suwon - near to seoul city. i just pass by there b4. not very sure what r the speciality there.


if u wan to know more about the places, just pm me.

now still winter (last 2 days snow in seoul according to my fren)
according to my korean frens, this year the winter might longer time.
i think by 26th april is spring(just start) already.

today i watched an introduction for jeju island show. wow! interesting.. i might go next time! only jeju island might takes 4-5 days to enjoy the whole island.