i1) want to take a taxi from the airport to your favorite Marriott hotel .... watch out ... downtown from PVG is approx 50 km and costs about 180 rmb ... some taxi's have a way of defeating the meter !!!
2) taxi from hotel to PVG ... recommend to take a taxi from the street not the hotel waiting area - for some hotels ie Renaissance Yu Garden, but ok from Marriott Luwan - street taxis are more likely to be honest
3) around town - street taxis are ok
and ... if you are cheated ... there is a phone number on the receipt to call the dispatcher to complain ... best if you have a Chinese friend to make the call - i've been reimbursed a 1/2 dozen times for turning the bad ones in on this ....