Shug's is probably the single best ice-cream parlor I have ever been to. I've enjoyed my time there every single time I've been, and their seasonal flavors are incredible. My go-to is the Brownie Sundae with Salted Caramel ice-cream. They even have alcoholic ice-cream floats if that's what you're into.
GameWorks is an arcade in downtown Seattle that I enjoy going to with friends. They have a wide array of different genres of arcade game. One standout area of the arcade is their huge selection of retro fighting game cabinets that I don't think you could find anywhere else in the Seattle area. I also have fond memories of playing Pump it Up, Mario Kart Arcade, and Minecraft Dungeons here with friends.
Most people will point you towards the waterfront when asked what the highlights of Seattle are. My favorite part of the area has to be the Great Wheel. I've only actually ridden it once (tickets are expensive!) but it was such an unforgettable experience for me that I'm putting it up here anyway. Not only does riding it give you such an incredible view of the surrounding area, even just observing it from a distance is really relaxing for me. It's such an important and consistent part of the skyline, second to the Space Needle (which is still difficult to pull off).