Here are the scenarios for how you could get to the airport:
Friend – cheap, convenient, and fast but not always an option
Bus – very cheap, but not usually very convenient, and pretty slow
Taxi or Towncar – very convenient and fast, but also very expensive
Shuttle Express Shared Van – convenient, fairly inexpensive, but usually pretty time consuming
To use Shuttle Express if you want to go to the airport, you call them up or sign on to the website. You tell them your flight information and your address and then they tell you when the shared van will be by to pick you up. It’s usually a window of time (30 mins or so) during which you have to watch and be ready to go. It’s also usually about 4 hours before your flight. I only live 20 minutes from the airport so leaving 4 hours ahead of time is very unnecessary and a waste of time. It usually costs about $20 or $30, though you can save money the more people you have in your party (it’s less per person that way). They do guarantee to get you to the airport on time however, which some people might like.
To take the Shuttle Express from Seatac airport to home, you go to the reservation counter down by the taxi stands and put your name in. Then you wait and wait and wait (depending on the volume of people who are also waiting) until your name is called. They try to group people into vans by where your drop off location is. Then you get in the van and hope that you aren’t the last person to get off, because, if you are, it could take you several hours to get home. This can be very very frustrating.
The drivers have all been nice in my experience (which is considerable), although a lot of them have been new to Seattle and were NOT familiar with the streets at all. Once, on my way home from the airport in the middle of the night, the driver asked me and the 5 other passengers to figure out amongst ourselves what order we should be dropped off in based on where we all live. This was really frustrating because we were all tired and angry and everyone obviously wanted to get off first. That was the last time I’ve taken the Shuttle Express because it was such an irritating experience. It’s now worth it to me to pay the extra $20 for a taxi, or deal with the slowness of the bus (if I don’t have a ton of luggage), or inconvenience a friend (if it’s not in the very early morning or late night).
Overall, the Shuttle Express can be useful, but I wouldn’t recommend it as your main mode of transportation to and from the airport (unless you’re just in Seattle for a conference or something, in which case it’s nice to get door to door service and cheaper than a taxi).