Going to Nanning end Sept for week. What's the weather like then ?

According to the past weather records, it would be warm even hot during that time, with the temperature ranging from 20℃ to 31℃. In most case, there would be cloudy days and sometimesvery light rain falls. I suggest you prepare summer clothes and a piece of long-sleeved shirt.

As for accommodation, here is my general suggestion without knowing your budget. Landmark Hotel and NN Hotel are worth a try! It is generally easy for dining and shopping nearby. The latter even has its own dining hall, offering both western and Chinese food.

If possible, I would suggest you book a hotel in Guilin in advance, because Oct. 1-7 will be Chinese National Day Holday. You may be unable to check in on the spot because all of them might have been booked.