From the Quito airport to the Quito bus terminal in the south of the city you are looking at 1 hour to one hour and a half travel time. Taxis from the airport should charge around $25.
We can help arrange a taxi upon request 24 hours a day fro here at the hotel near the airport in Quito.
You could also get to the city by bus by getting on the green city buses that leave from the airport. Get one going to the station in the south of town called Quitumbe. ($2)
This buses last stop is the bus terminal Quitumbe where you can catch to almost all destaintions in Ecuador.