I have been a regular attendee of the WDC for about eight years and work as a Technical Writer.
If you want *real* ballroom dancing and want to dance with the best social ballroom dancers in the State of Washington, this is the place. The best are there Sunday nights, and the second-best are there Friday nights. I have made it my mission to find out where are the best social ballroom dancers in this state; by visiting other ballrooms, dance studios, other venues, and by asking other dancers; and this is it. I know of no other place in the state that provides weekly dances where you will see 20 couples doing the Viennese Waltz at once--a difficult dance mastered only by experienced ballroom dancers.
In addition, the floor is large (3,000 sq. ft.) and well-maintained, the sound system is excellent, the music is almost perfect for social ballroom dancing, dressing rooms are provided, several world-class dance instructors are available for every skill level, and the attendees are friendly--even to those new to the venue and unskilled. It is open to all ages, and many young people (age 18+) attend regularly.
If you are not an experienced ballroom dancer, I suggest getting lots of instruction with private instructors (I do not instruct) and with group classes before attending dances there on Friday or Sunday nights. I particularly recommend the beginning group class on Friday nights at 8:00 p.m., because it is immediately followed by the regular dance, when you could see what the context and end-result of your instruction would look like. If you feel up to it, you could even participate in the dance, but at least you could observe more skilled dancers doing all the dances that inlcude the ballroom mix.
Parking near the ballroom is convenient, but mostly in pay-lots ($5 for an evening). You can bring a friend to help split the cost. After 6:00 p.m., you might find free street parking.
The WDC facility has been there since the early 1930s, and therefore shows its age. But it is definitely where Seattle's real social ballroom dancers go on a weekly basis.