Applied H-1B VISA at Guangzhou and got it after 2 working day, now it is the summary of what I learned from the last 3 H-1B VISA application experiences:
1. you can go to the consulate other than your original one, the one that covers your residency province. I asked the VO inside the window and he told me as long as you apply for the same H-1B for working for the same company, you can go to the city you have business trip. i.e. if your residency is in Guangzhou, but you need to go to Beijing for business trip, you can make an appointment in Beijing. Just don't tell the call center that your residency is in Guangzhou or they will not make the appointment for you. Prepare a company letter saying that you have to be in Beijing for business trip.
2. CITIC bank transfers service, if your H-1B VISA expired within 12 months, you can do it. In Guangzhou the process and timing is like this: 出国人员金融服务中心咨询电话：020-87586720
2.1 Monday you turn in your meterials
2.2 Tuesday CITIC bank collects all applications and transfer them to Consulate.
2.3 Wed afternoon go to consulate to leave your finger print
2.4.The folowing Monday check with CITIC bank and normally you can get the new VISA without going through in-person interview.
3. If you go to Guangzhou Consulate, the best way(clean, fast,safe and cheap) is Subway, go to final stop at Tian He East Rainway Staion (天河东站), take the exit to 天伦万怡酒店，you will be on 林和东路，2 blocks down the South （about 5 minutes walk) you will find the US consulate at 天誉花园
4. Your employment letter and recent salary check or stubs are aleays very useful to the VO.
Good Luck!