You should definitely go and see Mao, cos in DPRK you'll see Kim Il Sung, and, if he's ready, Kim Jong Il as well. Shame you can't visit Ho Chi Minh, but maybe he's in Russia for a respray, not sure. (Fly SU
via Moscow for Lenin's tomb to collect the set of embalmed commies!)
When I was in Beijing in 2010, young people offered a few times to have tea to practise their English. It's a total scam, you'll have a nice sit down with a couple of young ladies and drink some tea, then get a bill for $70. At least in Eastern Europe, it's champagne and the girls are strippers. Don't go to a secondary location with anyone who wants to "practise their English" OK
Other than that, enjoy China, North Korea, and the Il-62. I'm going in May, and, maybe September, sorry I'll miss you!
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz