Cost of taxi from Beijing International Airport to Crowne Plaza Lido Hotel for 4 people w/bags.

Generally speaking, it takes CNY 70-80 in the day time. And one cab can accept four passengers at a time. Thus if you don't have many luggage, you four can share one.
In addition, you can find official cabs at the following places in the airport:
T1: Outside Gate 1 on F1
T2: Outside Gate 5 to 9 on F1
T3: Please refer to the signs inside the terminal building