We started talking about going to Hong Kong and Seoul about a year ago. Originally we planned on going last fall but various circumstances led us to postpone the trip until now. Today we finally pulled the trigger and bought two tickets for March 27th through April 9th. We will be spending 5 days in each city. We chose this time since it seemed like the best weather for both places, or else we'll have to wait until next fall and that is TOO LONG. Hong Kong is apparently hell during the summer.
We do worry about Hong Kong. Late March is the start of their spring. It's apparently very humid with temperatures in the 70s and 80s, and it might rain a lot (fingers crossed it won't.) If it does in fact rain, we'll buy an umbrella and soldier through it. The consolation is there are a lot of indoor places to explore if there's precipitation. Seoul will be cooler with temperatures ranging from the upper 40's to low 60's, but at least it won't be raining. We'll be packing lots of layers and wearing sensible walking shoes.
The next step is to book accommodations. I have a lot of work to do!