Hi Silenze,
Thanks for the compliment. :)
Yes, Jeju also have fireworks display during New Year's Eve - New Year's Day. The location (if it's not change yet) should be in Sunrise Peak (Seongsan Ilchulbong) that adjoins Seongsan Beach. There will be some festival as well from overnight until dawn like the concert or Jeju traditional percussion perfomance called Pungmulnori.
For palaces, i would suggest Gyeongbokgung & Changdeokgung not Changyeonggung. Changdeokgung Palace has secret garden called Biwon, one of UNESCO World heritage site. Visiting to this palace is only by guided tour, and the palace close on Mondays. For more info : www.cdg.go.kr
If you're not really into UNESCO, you may visit Gyeongbokgung Palace, close on Tuesday, the palace have royal guard changing ceremony and you may have photo oppurtunity while wearing traditional customes for free, just go to the pavilion. For more info :
www.royalpalace.go.kr
Other than Jogyesa Temple, you may also consider :
- Naksan Myogaksa Temple : www.myogaksa.net
- Hwagyesa Temple : www.hwagyesa.or
- Bonguensa Temple : www.bonguensa.org
From the list, the closer one would be Bongeunsa Temple, near COEX mall and if you make a reservation by phone (+82-2-3218-4895), you'll be provided with a guided tour of the temple at anytime between 10am-5pm.
You can visit Yangji Pine Resort close to Everland.. Everland is a day trip but if you only have short time, you may go to Lotte World. Lotte World is indoor theme park and open till late at night. IMO, i prefer Lotte World. No doubt why most K-drama will use Lotte World rather than Everland, with location close to the city and you can shop as well :) Don't miss the Folk Museum, the museum close earlier.
For more info :
www.lotteworld.com
How many days are you staying in Seoul ?