I surprised that Singapore Airlines don't put a mattress on top of seat when laying flat. I didn't find their seats comfortable at all.

As JeCCo87 says Shenzhen has a lot to offer. We've been to Windows of the World a couple of times. One advice take a roll of toilet paper with you to SZ as there is usually none available.

Each time we've been up there, we try to get there very early just as it is opening, usually you don't have to wait long. Weekends are very busy.

I've never been aware of this as on a few occasions I've looked to no avail. 

Pjs is a definite. I'm travelling with Singapore Airlines in December bus class from BNE no 1st class is available from BNE with any airline and would love Pjs.