We're planning 2-3 weeks in HKG and China in late Sept early October.

Here is the current rough itinerary. All but Xian are certain stops.

Hong Kong & Macau
Beijing
Xian ?
Kunming

Any thoughts on this itinerary? Am I biting off too much for one trip?

I'm fairly certain our last week will intersect with a major holiday week. How will the Oct 1st holiday week affect our trip? We would most likely spend most of that week in Xian & Kunming under our current plan.