I live in Seoul.
From mid June to late August is the absolute worst time as far as climate. Tough luck on that.
If you can travel some, visit Gyeongju (Kyungju) for all the historical things. Do the DMZ but make sure you sign up for a USO tour (USO is north of Samgakji subway stop, west of Yongsan army base.) It's a better tour than the Korean ones.
If you wear suits much, get some made. Custom made, high quality material, two pairs of pants - $300 to $350. Custom made shirts for about $25 - twice the quality of the ones in the US. Also some good deals on other clothing - polo shirts, belts, ties, etc. I guess the socks are OK if you like synthetic fabric socks. I buy mine in the US.
The food is good if you have a taste for it but limited in range. Watch out for the on street (meals on wheels) places. You can get real sick real quick.
For night life, hang out in the Western places near Itaewon. Korean night spots are so expensive they will bankrupt you. A lot of them are $100 a table minimums. The girls are beautiful - at first glance. Subtract all the makeup, the plastic surgery, the anorexia and they are kind of scary. But you are only there for 2 months so enjoy.
Arrange to visit somewhere else on the way back. Depending on SARS - Hong Kong, Bangkok, Vietnam, Beijing, Bali, Japan (Kyoto) even Australia or New Zealand.
Here's my website for some odds and ends (haven't got a lot of my Korea stuff added yet).
My Website