I had good luck with 61Local in Brooklyn. http://61local.com/ The screening space was inexpensive, and they worked with me to set up a ticketing system for drinks, and a platter arrangement. While I probably spent too much on food & booze, I would’ve done that anyway.
Anthology Film Archives also has two really nice screening rooms. They’re a little cold in the winter unless things have changed since I was last there.
I’ve also talked with the NY Public Library, Queens Public Library, and various nonprofits about screening all/part of the show as all/part of an event. It takes a while to get these going (budget for at least one month of discussion, planning, etc.)
You want to put in some time sending out personalized emails to anyone you think would be good to have on hand for your screening. Cast & Crew, of course, but also crowdfunding supporters, people in the film/tv industry, any press.
If it’s a public event I find spending a little on FB advertising over a two week period, and creating an FB event page to support it, really does help turnout. Just tweak the FB ad as specifically as possible without getting down to just a handful of people.
If the venue will be creating the event page, work that out with them. I’d still recommend doing your own ad.