Came back from Seoul yesterday...
Weather in Seoul: Unpredictable. It rained consistently at night on 27th and 28th Feb.. very windy and bitterly cold. This week, no rain but still windy.. your face will be slapped with harsh cold with every gale of wind while walking on the street. It's sunny on some days only so for travelers going in mid-March please bring winter clothes. Daytime is about 5-7 degree celsius but nightime usually went below 3 or 4. I wear 4-5 layers everyday to keep warm. Seoulites said Spring will come in early April, so yea, be prepared!
Places: We didn't intend to shop in Seoul so we only went to Namdaemum, Dongdaemum, Yongsan Electronics Market, Insadong and Ewha Women Univ area. Don't really like Namdaemum cos the clothes not nice, food not nice... For facial, cosmetics, women clothings, korean lifestyle products, Ewha area is the best! Neverending streets and alleys with women stuff and you can negotiate prices too. Insadong is nice though food is not cheap, but abundant souvenirs there to bring home - do negotiate for better deals. The sellers are prepared for this.
Sightseeing: We only went to Gyeongbukgong and Bukchon Hanok Village. Regret not visiting Changdeokgong cos it's said to be nicer and less empty than Gyeongbukgong. We took the city tour bus and it's quite worth the price (10,000won). Do try

Accommodation: We chose Stay Korea 2 (http://www.staykorea.co.kr/english/01.html). Very nice, cosy and affordable place. It's situated in Hongdae area, near to Hongik Univ station. A lot of quaint cafes, cheap food and convenience stores. The caretaker (owner is always at Stay Korea 1) is very friendly, speaks good english and french.. She will also advise where to eat, where to visit and where to get tickets etc etc.
Our 11-day trip also expanded to Jeju and Gyeongju. Absolutely love Gyeongju and wish I can live in Jeju! Total cost for the trip is a lot more than expected but it's mainly due to transportation and food. We spent less on shopping except for souvenirs. Our main agenda is to sightsee and try their food

Will upload some pics soon..

Added on March 11, 2011, 12:05 pmOh, and, right now all over Insadong, Namdaemum and many places in Seoul are having big sales on winter clothes. I bought a long thick scarf for 7000 won in Ewha area. Boots on-sale are 10,000 won each pair; sweaters, coats and jackets start from 20,000 won onwards. It'll be cheaper to get them there for travelers going in March than buying here.