I'm flying Air China coach/economy from BKK to PEK, then PEK to SFO. There's a 14+ hour layover in PEK.

On my way to BKK, I had a horrible time at PEK getting through immigration and security (the lines were long and not staffed accordingly, and I was stopped at immigration, phone calls made, and pulled aside and stared at by several Chinese authorities and my passport taken behind a door before finally being set free, I have no idea why - it was unnerving) and on to my connecting flight - took 2 hours and barely made it by the skin of my teeth.

I was originally planning on doing a layover tour to the Great Wall, but none of the companies I've contacted have even responded to me over the past two weeks of contact. I'm also afraid of timing giving my troubles when I passed through the first time, and that my flight from BKK lands after midnight and the next takes off to SFO just after 4pm.

Is a layover tour feasible? How do I even go about doing this? Is it safe? I am a single woman, mid-30s, traveling alone.

And if not a tour, can I purchase one-day/time access to the Air China or a Star Alliance lounge? How/where do I do that? I've done it easily in the past with United, but I can't seem to find the answer, despite Googling a ton.

Any help is GREATLY appreciated!!