The Portland transportation system is fantastic and it just keeps getting better. Here I'll give you a run down of what is available for you to use so you can leave your car parked at your lodging and go almost anywhere you want to go.
This was Portland's first project to improve the Portland transportation system beyond the public bus system. It began in the 1980's and it just keeps expanding.
On MAX you can travel from Portland International Airport into downtown Portland, go east to the City of Gresham, go west to the City of Hillsboro or go south to Clackamas. Trains run between every 5 to 15 minutes between the hours of 4:30 am and midnight. They are clean and even though they stop frequently they are fast.
As an example, let's say you are staying in a hotel in downtown Portland and you wanted to go to the Oregon Zoo or the Rose Test Garden in Washington Park. MAX will take you right there. The trains are accessible for the mobility impaired.
The MAX network has become more complex over the years which makes it difficult to describe completely here. It is best to take a look at the MAX website where you can see maps of the routes and find instructions for how to ride the train and charges.
Now MAX is nice but it can't take you everywhere. The Portland Streetcar can take you a lot more places and the fares are the same as on MAX. The tickets are interchangeable.
If MAX can't get you where you want to go, take a look at the streetcar route to see if it solves your need.
Now from the Portland Streetcar at the South Waterfront you can take the Arial Tram to the top of Marquam Hill. This is where the Oregon Health Sciences Center is and the Veterans' Hospital. Even if you don't have a reason to go to one of the hospitals on Marquam Hill you might like to take a ride just to get a panoramic view of the City of Portland.
The Willamette Shore Trolley is an authentic antique trolley that travels from the South Waterfront along the Willamette River to the City of Lake Oswego. The trolley runs every two hours mostly on weekends but also on Thursday and Friday during July and August and also on Friday during September. The trip to Lake Oswego takes 40 minutes each way. You will want to do some shopping and maybe have some lunch in the little boutiques and restaurants around the lake before your return.
Portland has a Zipcar system where, if you are a member, you can pick up a car in dozens of areas around the city and drive where you need to go. It is really the thing to do if you only need a car for a few hours for a short trip.
You can hire a private car to pick you up at PDX and take you to your hotel in Portland, Beaverton, Lake Oswego, or Tigard. Your driver will meet your flight so you don't have to wait for a hotel shuttle or find a taxi. Then when you go home, you will be picked up at your hotel and arrive at the airport in time for your flight.