Confused about Visa requirements

We have confirmed flights booked from Siem Reap to Guangzhou to Shanghai to US all occurring in a time frame less than 24 hours...what are the chances of receiving a pass at the airport...in GZ to leave the secured area to go and sleep in the hotel (Pullman)for the night....since we are stopping in 2 cities we don't qualify for the 72 hour Transit Without Visa....will the airlines give us grief about getting on the plane without some kind of formal visa in our passport?
The airlines say you need a visa to be safe..the embassy even says it is best to get one but it Is expensive to have just for passing through for less than 24 hours...