The average temperature is of 18.6 to 24.9 in September. It is cool and comfrtable. As to hotel, it depends in your hotel budget. There are many star hotels in Qingdao. Grand Regency Hotel Qingdao is a five star hotel which is very good.
The first must-see attraction is Zhan Bridge (Zhanqiao). Golden Sand Beach and the Badaguan Scenic Area are also worth visiting.