Hi ZZTop
None of the evenings are completely free so you might have to decide which activity you least want to take part in and see your friend then. I'd suggest Day 7 in Xian - I forgot the acrobat show in my previous message!
Beijing Day 2 - welcome drink (bear in mind you will be jet-lagged)
Beijing Day 3 - Acrobat show (very popular - it would be a shame to miss this)
Beijing Day 4 - Peking Duck Dinner
Xian Day 7 - Dinner (this may be the best night to do your own thing)
Xian Day 8 - folklore show
Xian Day 9 - farewell dinner
Kind regards
Olly, your editor