Mark,
I have the same challenge - also in Seattle. The former owner of our property had a dug well about 5' deep. He used a (dry) jet pump to get water into a pressurized tank and then somehow the water would shoot uphill (30')and supplied his small home and landscaping water needs. Now, the pump needs to be replaced and I've searched all over town to see if someone could advise about how much more I could get from a 3/4 hp jet pump vs. a 1/2 hp pump. Let me know if you find someone to help!!! I am also researching how to build another dug well at another site with water flow of 9+GPM. And finally, I'm researching how to get a pump to turn off with the use of a bobber gizmo which I'm sure someone sells?!?!

What I have found so far:
*Check out H.D. Fowler in Bellevue for pumps. Their sales rep.s are helpful.
*Forget calling well drillers. They can't help you without permits from KC, etc. Or, if you find someone, pass their name along!!!!
*My understanding of the pressurized tank is that it doesn't necessarily get you more PSI, but it just gives your pump a rest so it doesn't run continually.

Please keep me posted on any info. that could help. Thanks.

Susan,
I have figured out what I need for my system. The first thing I did was to do some homework. I read some basic information on pumps at http://www.irrigationtutorials.com/.
Then I went shopping. I got lucky in finding someone at a local Lowes that knows about pumps. He helped me select a shallow well pump that will do what I need. He also suggested that I buy a pressurized pump, as you have recommended above. I haven't bought anything yet, but I know what I need and I know where to get it when I'm ready to install it.
-Mark