From Thailand to the US via Guangzhou and Shanghai

I will flying from Chiang Mai, Thailand to Shanghai on China Eastern Airlines with a 7 hour stopover in Guangzhou. I will then be in Shanghai for 36 hours and continuing on to Los Angeles. Can I leave the airport in both Guangzhou and Shanghai during my stopovers under the Visa free policy? I will have confirmed tickets for all onward travel. We are a group of four with three US passports and one South Korean passport.