The Hilton Portland web site provides information on travel and area attractions.
The Portland Airport has connections to the MAX Light Rail system. The Red line can deliver you at low cost quite near the Portland Hilton. Look here for a topological map of the stations, and look here for a Google map of Portland, which shows the Hilton and nearby stations.
In addition, you might check out:
Portland Oregon Tourism Travel Guide to Portland (NY Times) In Portland, a Golden Age of Dining and Drinking (NY Times) In Portland, Cultivating a Culture of Two Wheels (NY Times) Group hopes to rename Portland street after Douglas Adams