The Trust for Governors Island says they're extending the island's hours from 5:30 p.m. to 10 p.m. so visitors can hang out at the island's new-ish park, which boasts famously beautiful views of Manhattan and the New York harbor. Food vendors like Little Eva's, Governors Island Beer Co. and Blue Marble will also extend their hours so you can dine on the island, or bring your own food if you prefer [to save money]. The last ferry to Governors Island leaves Lower Manhattan at 8:30 p.m., and the last ferry back is at 10 p.m.
Lest you can't make it to the island, or the little weather app raincloud over Friday scares you away, Governors Island still has some life in it for what's left of the summer—there's Civil War Weekend from August 12th to August 13th, for instance, the NYC Volkswagen Traffic Jam on August 20th, the Jazz Age Lawn Party on August 26th, and the NYC Unicycle Festival from September 2nd to September 3rd, which is certainly a sight to behold. The Trust will also extend hours again on August 18th.
There's a full list of events on the Governors Island website, and see here for a full guide to the 2017 season. Note that this year Governors Island will stay open through October 31st; perhaps one day we'll be able to enjoy winter sunsets from The Hills too.