How to obtain Visit Visas for my family as we intend 1 week visit to Beijing & Shanghai

I am a Manager of a leading Private Bank. I have made many visits to china specially to attend Trade Fairs . My wife is involved in importing optical goods but she has never visited before due to our childrens education matters. We have arranged a 1 week visit( Beijing & wuxi ) and also with intention of a Business trip. Since it is Shool Holidays We all ( myself. wife and 3 children ( 2 sons & 1 Daughter)aged 17, 11 & 8 years need to make a visit.
If required I could get one of our suppliers to send us an official request/ Invitation.
Since I have only few days left please knidly advise me the actual procedure for us to get visas. Please advise me. Some people told me that You NEED to submit something called 'Visa Notice' issued by Foreign affairs Ministry. Is it required?-Pls advise me early.I am planning to leave by 12th April and return is expected 19th May.