If you go up to the departure level (level 4), it is very easy to get a taxi that is dropping someone off without having to wait in any line. You will also save some money. Our condo is located off Sukhumvit, nearby Emporium, and I generally only pay 175 Baht for the fare, plus 25 Baht for one toll-way. It takes 20-25 minutes late-night when there's no traffic. Never had a problem doing this.