Hey fcolliga,
First, I think patience is in order. My mileage didn't pick up until maybe 5000, and I think it was me more than the vehicle. I would expect you got get between 28 and 30 in Seattle, unless you are a successful (read nutty) hypermiler.
As far as driving style, I would recommend some fairly simple methods.
1. Don't accelerate rapidly. That is, keep it in the 2000 - 2800 rpm range.
2. Don't accelerate too slowly. See above.
3. Don't drive aggressively.
4. Instead of the classical pulse and glide, try to back off the throttle to the point that just maintains your speed. You may need to re-accelerate some, but you will find that there is a fairly large range of throttle input that maintains your speed.
5. Don't drive aggressively. Did I repeat myself?
Patience is a virtue, and it increases your mileage.
The posted methods for hypermiling are great and all, but are sometimes more trouble than they are worth (to me). And some of them seem dangerous to me. I will say, though, following a group of vehicles, or a truck at a reasonable distance on the freeway does make a difference. Always passing, or being in the lead definitely hurts your mileage.
Good luck!