Nanning is a beautiful city. You will surely love it.
Guangxi is very hot and rainy from May - September. Cooler and drier Oct - April.
You won't find much english spoken there. Be prepared. Have your hotel's addresses written in Chinese as very few taxi drivers will speak english. In order to ensure that your hotel staff speaks english, you'll need to stay in a four or five star. Be patient, speak slowly. If they don't understand you, rephrase what you are trying to say.
I would recommend flying to Shanghai and then train to Nanning.
You cannot fly into Shanghai and fly to Nanning from the same airport. Shanghai has two airports one is domestic and one is international. See the countryside from the train.
When you are there, depending on your free time available, take trips to Guilin, Beihai and Haikou.
I envy you. Enjoy
Guangxi is very hot and rainy from May - September. Cooler and drier Oct - April

Before I went to China, I had travelled to twenty or more foreign countries. China was a mind blower because things are very very different there. Even with some ability to speak Mandarin, I had a hard time on the road less travelled (ie, Nanning). Keep an open mind, be patient. People will be very friendly and bend over backwards for you. Be humble and grateful.
Things are often not what they seem in China. Beware of people who speak excellent english trying to befriend you. The will spend hours cultivating a "fake friendship" before trying to con you.
Best to avoid topics like politics and traumatic events in recent history. Most Chinese will not trust you enough to discuss these topics.

Thanks for the great info. My woman mails me pictures of Nanning from time to time, it is such a beautiful city! Well am not worried about hotel and stuff like that, will be staying with her in her house. She is studying very hard on english so that we can communicate without others help, in the mean time I am trying to learn mandarin so I can at least meet her halfway with the language situation. Thanks again for the great info!!!!!!!!