I’m a huge fan of riding Trimet trains and buses. Prior to the airport Max (aka the Red Line), I used to ride a Trimet bus to the airport. The line number escapes me, and the bus actually worked fairly well. However, buses are more challenging to navigate, particularly if you’re coming to a new city. They are also typically viewed as dirtier and scarier than trains. The airport bus, however, had the advantage of taking a fascinating trip through Eastside Portland while the airport Max pretty much moves you along freeways.
Nonetheless, I appreciate the airport Max line and was very excited when the train line opened in 2002(?). Nothing is more satisfying than taking a train that is moving faster than gridlocked freeway. And the convenience of the Max airport station nicely complements traveling with carry-on luggage. Walk off the plane and walk on the train.
It’s an All Zone ticket (NOTE: Trimet no longer uses zones), and there is some value in having a ticket ahead of time (NOTE: or use their phone app) so that you don’t have to fuss with the ever problematic ticket machines.