Many streets in Seattle are numbered & given directionality. It can be quite confusing to the visitor or newcomer until you understand the "key".
In general, streets run east-west and avenues run north-south. The avenue numbering system begins at the waterfront and ends near the Cascade Mountains.
The directionality or compass direction on the street follows this general guide:
Downtown streets have no directional designation attached to them, but when you cross I-5 going east, most streets and avenues are designated "East."
South of Yesler Way which runs through Pioneer Square, streets are designated "South."
West of Queen Anne Avenue & North of Denny Way, streets are designated "West."
The University District , in general, is designated "NE" (Northeast);. The NE region is bounded by the Canal / Montlake Cut to the south, 1st Ave NE (and to some extent, Green Lake) to the west, and Lake Washington to the East.
"NW," which included the Ballard Neighborhood is bounded by Puget Sound to the west, the Lake Washington Ship Canal to the south, and 1st Ave NW to the east.
"North" is basically inbetween NE & NW
The best way to get around downtown is on foot! Every thing is fairly close by. However if you one of those who like to keep your feet low milage, then I recommend either the Monorail which is excellent within downtown or the metro bus which is a fantastic commuter friendly system. In many parts of downtown, its fare free zone!
Walking is a breeze and the buses are easy to negotiate. When all else fails ,taxis. Although sometimes difficult to find and more expensive, a good third choice. Do not rent a car . Traffic can be annoyimg and everyone charges for parking. The money you save on rental, parking and driving hassle is compensated with easy public transportation.
When you are driving to the Space Needle, make sure to park at the northside of the Space Needle because there is a street parking there and it is cheaper! It's located past the bamboo-look-alike artwork and past the parking lot as shown in the pictures.
While the bus system in Seattle is FAR behind other large cities in the US it is becoming easier to use. The Seattle Metro website will make your life a lot easier.
If walking is in order (as it should be, do not rent a car if you do not want to pay a fortune for parking) you may find yourself asking a lot of directions. Downtown however, is fairly easy to navigate. The street numbers go up from the water. And if you get to Yesler you are in SODO (south of downtown). If you walk too far the other way and get to Denny WY you will be by the Space Needle and Key Arena. If you start to walk up a hill (after about 9th when the numbered streets end) you will be on First or Capitol Hill. Downtown is fairly small and if you have the address to where you want to be it should be fairly easy to find.
All the major tourist sights in Seattle are within walking distance. Having said that, it does rain quite frequently in Seattle, so you could always hop onto a bus which is free within the downtown area.
Definitely bring sneakers or comfy shoes to get around this hilly city. It's definitely not for the weary, but I thought walking around was the best way to see all Seattle has to offer. Not a shop, street corner or building was missed in my trip. If you are in shape & can handle the treks all day, definitely walk all over. Queen Anne Hill is a big one, but the pictures I took from the lookout were so worth it!
Seattle is a pretty easy city to get arround on foot despite its many hills. Bring a good pair of shoes and some water and you should be ready to see the city. If you find yourself too tired to make it back to your hotel you can always take one of the many transportation options back. You'll get to chose from bus, taxi and even monorail in some parts.