I never had to wait more than 10 minutes and that was on a Friday night and it's a secret to visitors, not to 20 something NY'ers, Long Island Guidos and Hipsters. Or maybe I misunderstood this thread.
I love the beergardens... but these days you've gotta show up at 2PM or you're waiting on line. Also, they'll throw a cover charge in there every once in a while.
Anyway, if the establishment in question has been put into a video game (Steinway Beer Gardens/GTA IV,) then i don't think you can consider it a secret anymore.
Theres a beergarden in Forest Hills that is kind of nice... i think its next to a really nice twin movie theater thats also pretty cool.
Cherry Valley Deli in whitestone, queens has amazing chicken cutlet sandwiches 24 hours a day. the beast: chicken cutlets, swiss cheese, bacon, and onion rings on toasted garlic bread with hot sauce and gravy. if you go at 3AM, there is a 100% chance you will see "Long Island Guidos."
And finally, this isn't a secret really, but if you haven't gone to the Lemon Ice King of Corona yet, please be sure to get there before the summer is over.
Thank you.