BIKE PORT is located in downtown Seattle, is run by (and next door to) the Bicycle Alliance of Washington and also hosts the JRA Bike Shop.
BIKE PORT is affordable, convenient, and secure bike parking. Yes, there is "free" bike parking just about anywhere you can find a pole-- but would you leave your nice panniers in the street? What if you're 'geared up' in 'cycling clothes' because you've been riding for an hour, and need to change and freshen up? Using Bike Port takes the stress out of bike parking if you don't already have an indoor place to secure your bike and use a restroom.
Parking is free on weekdays, 9am-5pm. Buy a pass for 24/7 access! For my 'sporadic use' membership, I am only paying $2 for each time I park after-hours!
There is a public work stand and tools for you to use (as well as a professional mechanic at the in-house bike shop if you don't know how to fix it yourself).
The bathroom is big enough to swallow up you and your bike!
(No showers yet, but they're working on it.)
Security cameras. While the security of your bicycle and belongings is not guaranteed (you should still lock your bike and take your valuables), the odds of theft are much lower. Bike Port is staffed 9am-5pm on weekdays and only members can enter using their key-card after hours.