The biggest thing about seattle that makes it so great is the people/culture/environment surrounding it. Its not the east coast, which is filled with alot of rude people who live their lives uber competitively. Its not the south where there is still a ton of religious freaks. Its not the southwest where its a million degrees the whole year. Its not the midwest where its negative a million degrees for half of the year. Its not like southern cali (L.A specifically) where all of the people suck. But there is a balance among the people who live here.
Yes it does rain quite a bit, but that rain is the reason its so wonderfully green here (2nd reason its great). When its not raining it is absolutely beautiful, and you appreciate it more because you dont experience it everyday.
This is going to sound pretentious BUT i'll say it anyway. There is alot of money in the area with Microsoft, Amazon, Starbucks, Boeing, ect... Because of this the overall quality of living here is pretty good.
IIt has great proximity to all of the mountains in western washington you wont spend more than 3 hours (without traffic) driving to a mountain, and those are the ones that are far. Snoqualmie Pass and Stevens Pass are between 45 min- 1.5 hours away a 3 hour drive to canada (5 to whistler) and a 6 hour drive to hood.