This is another park I spent a lot of time in as an undergrad. The chains are very long, there aren't very many small children present, and the nearest late-night falafel is within a 15-minute walk.
Location: 7th Ave NE & NE 50th St.
Number of swings: 4 regular, 2 baby
Ground material: Wood chips
Chain length: Long.
This is a great place for late-night swinging. You can also scope out the street scene once you get going really high. If you bring friends who hate swings (and are super lame because of it), the tables in front of the swings have chess boards printed on them.
How to get there: #66 bus (Southbound) stops on Roosevelt St., Northbound stops on 12th.