Joe put together a pretty good summary of Portland directions. Our many freeways and sometimes unfamiliar naming can make it confusing for visitors.

When I first moved to Portland, navigating about was bewildering with the likes of SW (southwest) this and NE (northeast) that!  Further, a five digit address format was unfamiliar.  Finally, a co-worker sat me down and explained the logic.  If you are traveling here soon, you may appreciate this primer even if you have a GPS (by all means bring one if you have a portable or get a rental with one installed!!)
 
The SW, NE business comes from two lines drawn through downtown Portland; east and west are split by the Willamette River and north and south split by Burnside Street.  Hence the four quadrants split by these two lines are (in clockwise order) NE, SE, SW and NW from the center of the Burnside Bridge.  So many adjoining streets and in fact, several communities and cities can be in one quadrant, like the Gonzales home (SW Hart Drive), the Bunker home (SW 209th Ave) and even the church (SW Mill St) are all in the same quadrant.  The airport is in the NE and you can find some very cool shopping and dining on NW 23rd as other examples of significant landmarks in other sectors.
 
You will find many streets numbered from the Willamette River.  The church is on SW 4th Street and is four streets away from the river to the west side.  Eric and Jade live on SW 18th and this same numbering referencing goes out to the Bunker home on SW 209th Ave, or 209 streets away from the river.  The numbering goes out in both directions from the river so the NE, SE, SW, NW goes with the street numbers.  To the east, this goes to about 240ish but to the west is goes to the 3 or 400 series.  The airport is near NE 82nd so to get to the Bunker home, you go 82 streets west to the river then 209 streets west to SW 209th Ave for a total of 291 streets in the western direction.
 
Addresses pick up the street intersection if they go north/south.  The Gonzales home address is 17885 SW Hart, so the cross streets are 178th and 179th, in fact, the house is at the intersection of Hart Dr and 179th Place.  Knowing this can help navigate by reckoning if needed. 
 
In Downtown Portland, streets north of Burnside (or NW) have the first letter in alphabetic order.  They begin with Ankeny, Burnside, Couch, Davis and so forth up to York.
 
Now for fun, downtown is riddled with one way streets so you may have to go one street short or one street long of your destination because of this.  For extra fun, there is plenty of construction going on downtown so the street you want to use is closed and you need to work around these obstacals.  This creates a challenge for surbanites even with familarity with downtown navigation.
 
All in all, use a GPS as much as possible.  Be sure to enter SW or NE designations for street names or you will confuse the simple machine. 
 
Hope this helps!  See you all soon.

Love,
Jade and Eric and the rest of the GonzoBunk bunch