I would prefer to pay upfront for 6 months (or a year) rather than hand my credit card over, and authorize monthly payments. These automatic payments can be hard to stop (lots of horror stories about big franchises taking additional months to cancel a membership, or charging a cancellation fee, etc). If I join a gym, I'm going to exercise, period. I am certain that a year from now, I'll still want a gym. So paying upfront is only a risk if the gym sucks, or goes out of business. I can usually tell if the gym is no good (and I can tolerate a crummy place, if there are no other choices). Health clubs are a big source of consumer fraud (pre-sales but then the gym never opens, etc) so there are laws that are somewhat protective. If the facility is big, it's unlikely they will go out of business, but these gyms seem to be the type that are hard to cancel (look at reviews on Yelp or Google for horror stories). So, I prefer paying upfront.
Since you guys are talking about going outside of Jackson Heights, I liked the gym called Phyzique in Woodside (I only visited). Not huge but medium-large, clean, good selection of machines and free weights, near the 7 train 52nd street station (located on 50th street just above Roosevelt). I don't recall if they have a separate room for aerobics (I mainly use the free weights) -- sorry about that, aerobics folks. Maybe call to ask. Worth a visit in-person. They have treadmills, bikes and steppers if I recall. Nice facility. I was there in the afternoon (it was quiet) but like every gym, I suppose it gets busy between 6 and 9pm.
http://phyzique4life.com/I also liked Big 6 Gym in Woodside (on Queens Blvd) which is large, very well-equipped, and they do have aerobics classes. Again, I only visited during the daytime. You can expect an after-work rush. Formerly a Golds Gym or maybe World Gym (?). It's in the Big 6 mall.
http://www.yelp.com/biz/big-six-fitness-woodside(I didn't want to promote these gyms too much, because they are not within the confines of JH. But since I see other people mentioning Sunnyside and Astoria, I thought I would mention them again.)
I want to move to the area, and a good gym within walking distance is non-negotiable, so I've been visiting different facilities to see what they offer. It's a definite drawback that JH doesn't have more. I'll check out Retro Fitness at some point soon!