I bought a two family on Beach 101st in Feb 2008.
Anything to the right of the bridge at 96th is up and coming, anything to the left is a long shot.
High School is/was crappy (Beach Channel) due to < 96th students but they are restructuring it, and there are private school options. Much new development in Rockaway Park which is attracting a large range of working middle class people.
I think that Rockaway Park is a good 5-10 year investment. The subway line is there, the beach is there, and eventually people will want to stay in New York but also be near the beach. So I think that schools will matter less to people who want to retire in NYC with the ability to get around by subway, but be near a beach.
Lower than 96th has simply too many projects that are going nowhere. That Arverne by the Sea has units going begging on Craiglist for like 1700 to rent a two bedroom, 2000 for a three bedroom because people overpaid to be pioneers, and now need to cover their costs by gouging renters. But in Rockaway Park, you can probably pick up a decent size (2200 sq ft) newer two family for 508, which is what zillow says mine is worth, and the numbers work much nicer.
So basically I recommend Rockaway Park, if you do not need a great public HIgh School school right now.