Big picture curbs are dope for sure. If you want something like that closer to Ballard, hit up the Ravenna curbs (under the I-5 overpass just near the Ravenna Whole Foods, but you’ll need to skate it on a dry day).
As for covered stuff, UW garages beneath red square are great as mentioned. The best level is C5. There’s a long manual pad on the level below that leads towards an exit. Convention center has nearly two blocks on Pike that are undercover with good flatground and some banks, stairs, razor ledges and rocks to skate. Other than that, plenty of random parking garages to explore in the area. ATS (the park in Fremont) is chill when it’s not crowded but I only like to go when it’s after hours.