The gayborhood in on Capitol (Cap) Hill. Broadway is the main drive. Look it up on Google maps. Google the gay places in turn, see what they're doing while you're there.
As for general tourist attractions, there's the Science Museum near the Space Needle. The park is also nice, plus you get to see the iconic Needle. Not sure if it's open to visitors at present. There's a museum & gardens at Volunteer Park, itself a notorious gay cruising location.
Pioneer Square is good for local color. Google for seafood restaurants right on the Sound or Union Lake - some are wonderful. They serve the fresh catch as it comes off the fishing boats. There's also an outdoor Seattle fish market, but you've gotta have a way to prepare stuff you would buy. Still, might be fun to see. And I THINK there might be a couple of places that actually serve prepared fish right there.