In Seattle, there's a nice park along the ocean (the sound technically), also an outdoor sculpture park there too. There's some cool bars and cafes along the piers by there, as well as some really good seafood. There's a ferris wheel on the pier that isn't terribly expensive, but pretty much anywhere along the water is gonna have great views at sunset or sunrise. Lake Union has a lot of boats and a boat museum, Green Lake is also pretty nice. The Fish Market downtown is pretty neat, lots of cool little shops in there, and local food vendors. There's a gum wall you can stick your gum on nearby. Someone mentioned the arboretum, and I second that. The Frye Art Museum is free
As far as things that cost money, I dont really think the Space Needle is worth it. There's a long wait in line, its expensive, and if you've been on top of a tall building before then you're not missing much. On the other hand, I think the Chihuly Garden is money well spent if ur into art. Some pretty trippy stuff in there, its real fun on hallucinogens lol. I also really like the Seattle Aquarium. In general, I'd suggest getting a bagel somewhere and checking out different cafes. Eltana is my personal favorite, tho Rubenstein's and Blazing Bagels aren't bad either. Capitol Hill is a cool neighborhood to check out that's very progressive and queer friendly. It has lots of neat shops. You can go to Cal Anderson park if you wanna see where the CHAZ (capitol hill autonomous zone) happened in 2020.