Along with the above noted suggestions to choose the restaurant based on where you will be located at the time - with which I heartily agree - I would also like to add that it may boil down to a preference for the types of food served.
WCC seemed to offer alot of BBQ style food - think BBq Ribs, baked beans, corn bread, etc. They also have an eclectic mix of Pacific NW items such as PNW style crab cakes (whatever that is), trout, and other fish. The theme escapes me sometimes. Without meaning to sound picky, we did not care for the BBQ items - Think BBQ sauce spread over flacid, uninspired ribs.
50's PTC seemed to offer more of a 1950's style diner fare - fried chix, meatloaf, etc. We thought the food was better here - but not by a landside.
Both places promote the antics of the waitstaff - as has been noted, which can definitely be hit or miss. The one time we dined at WCC we were seated way in the back behind large pillars, we didn't see any of the "action" & our waitstaff was less than enthusiastic. I'm told this can happen at both restaurants, tho we've been very luck at PTC.
IMHO we had a much better time the 3 times we've dined at PTC. Conversely, once was enough at WCC. YMMV.
Base your decision on proximity and on type of food - and have a great time!