Dahl Playfield is pretty cool. It's next to University Prep, but don't hold that against it. There's some nice nature-y landscaping present.
Location: NE 77th St & 25th Ave NE
Number of swings: 2 regular, 2 baby
Ground material: Pebbles
Chain length: Long.
Note that the ground material here is pebbles. I think I prefer this kind of ground material. Most of Seattle's parks contain wood chips as a ground material, and I like that as well. Wood is absorbent of forces, soft, wood-smelling, but I do appreciate a good alternative. Sand is hard and gets into your shoes and every crevice of every thing you have. Rubber material is soft and cushiony, but it's a single piece, with similar shearing-action pain as asphalt. Pebbles provide a similar cushion-like absorbency without the stick/slivery mess of wood. And the sound of jumping on them! Kssssh. I like pebbles. (yeah, pebbles get stuck in your shoes too, but whatever. What do you think of ground materials? Feel free to discuss in comments section.)
I really liked Dahl Park. or Playfield. or Park adjacent to Playfield. I like the landscaping, with the pond and all, and it makes me wonder if it's natural. Honestly, I wouldn't be surprised either way. This park is spacious, away-from-it-all, and the playground seems like a relatively recent version/upgrade compared with other Seattle parks.
How to get there: Bus route #68, 378 run along 75th & 25th. The 72 runs nearby on Ravenna.