Kevin
I've not been on this particular holiday, but 30kg is more than most airlines allow in my experience. I'm assuming you're travelling economy, and haven't upgraded.
Why not give the call centre a ring, they will be able to tell you the limit for both the international flight, and any internal flights within China.
30kg is also a very heavy suitcase to lift !
As to actual luggage, I would suggest that your main case is fairly sturdy, as they get thrown around a fair bit by baggage staff, but not so large that you can't handle it. A lot of cases are solid construction, but they tend to be heavier and more expensive, up to you. It's needs to have wheels and a carrying handle, but they nearly all do anyway. Go into any decent shop and see what's available.
The bag you take on board, needs to fit into the overhead lockers, and you need to be able to lift it easily, so it can't be that big. Again the JY call centre can probably tell you any limits on size, but most decent luggage shops will sell bags designed to go on the plane, that are the right size.
Personally all I tend to take on board is any important documentation I want to keep with me, expensive items like my camera, plus anything I want on the plane (reading glasses, water bottle, MP3 player etc), plus a change of clothing (just in case my main case goes missing - not that that's ever happened to me, on dozens of flights).
I've been to China (not with JY), and every hotel we stayed at offered a laundry service (at very, very low cost), so that is one way to cut down the amount of clothes you take. Also, I guess, you could wash things yourself, but drying that could get a bit "interesting"
Enjoy the holiday.
Stuart
