Chengdu Layover

Hi,

I am Traveling from Lax to BKK and have a layover in shanghai (4 hours) and chengdu (22 hrs). We are wanting to leave the airport and spend time in Chengdu. Is this possible? and do we need to apply for visa free transit in shanghai or chengdu? we dont plan to leave the airport in shanghai only in Chengdu.

Thanks!