I can recommend a few. Kenmore is in the process of major redevelopment and is a suburb just north of Seattle. See http://www.kenmorewa.gov/lakepointe . The entire waterfront area (which is now industrial) is currently under feasibility to become developed with shops, restaurants and high-end residential etc. Investing within proximity would be worth looking into. As far as timeline, my Councilman neighbor suggested 5 years until they start digging and 10 years before we will be able to enjoy the new waterfront village.
The City of Everett is also in the process of redevelopment. http://www.portofeverett.com/real-estate/developme... In relation to Seattle or even Kenmore/Bothell, prices are still cheap in Everett.
If you're thinking urban Seattle, I'd look into anything close to the Light Rail stations that are slated to be built. Some examples of areas to the North that haven't been completely exploited are Nortgate, Shoreline, Mountlake Terrace and of course Everett to the way North. To the South, I'm a big fan of Burien as private development is in the beginnings of a boom down there.
Feel free to reach out if you want more info about the Seattle area. I've lived here for over 30 years, and specialize in working with investors and developers in the area.