Is it a bad idea to plan to visit Beijing in the week prior to National Day holidays? Too crowded?

Thinking of going to Beijing 20th- 25th September, then going on to Chengdu and then Yangshou. Planning on flying out of Guilin around the 6th October. Do you think we will be able to avoid most of the crowds foe National Day celebrations? Travelling with 3 children.....

Thanks