I arrived late at night, and ended up just taking a cab to the hotel. Didn't bother with the shuttle bus as you've got to walk out to the parking lot and we were tired, signage showed that the train to Asia World Expo is in a completely different spot to the Airport Express train to the city, so we didn't want to bother with that either.

The next morning, I did find the shuttle from the hotel to the airport quite convenient. Leaves right from the lobby and drops you off right in front of departures.