Interesting. I honestly don't know whether or not there are age restrictions that apply to hotel guests in China, but I'd be willing to bet that, even if there are, work arounds are not especially challenging.

In any event, based on the updated fact set, I now recommend the 2.5 hour layover in PEK if the following conditions are met:

1) same terminal
2) single ticket
3) willingness to risk not arriving in Sweden the following morning