It really all depends on whats important to you.
Whenever I purchased my primary residences, I always looked at it as an investment and they have always been a good one, but I had other things that weighed in when I purchased them...
When I look at investment properties I look at cashflow and its appreciation potential and make my decision based on that, but with primary residences its a bit different.
My last house that I purchased, I could have bought a larger home with a lot more rooms, in less expensive area and had my mortgage paid for that way, but I chose to purchase in more trendy/expensive area with less room. The house that I purchased was so small having roommates was not an option, so I paid a lot per month to maintain the house, but I really enjoyed living in the area with lots of amenities near by. In the end, it was still a good investment because the house appreciated a lot in value and I ended up selling it for a huge profit .... But I could have saved alot more on monthly payment if I had chosen to live in a bigger house at a different location.
If, gaining most bang for your buck is the most important to you, I would try to purchase a home with more rooms (More rooms, more rent) and I would also do some market research to see what the rooms are going for in the areas of interest. (I would think West Seattle would be higher than Shoreline) Shoreline is known to have great school district, so you will probably attract more families... If this is the type of demographic that you are looking to rent to in future, maybe that would be a good place for you...