Hampstead if you mean Hamptons, isn't a suburb. :) But maybe you refer to somewhere else. My impression is that Nassau is in decline. Westchester will always be Westchester. I was in Chicago about 5 years ago. I was amazed that the ghetto between downtown and the University of Chicago had been largely cleared away, and become mostly black middle class. The other big change were the Hispanics. All of those white ethnic neighborhoods on the Southwest side going to Midway airport had become Hispanic. When I was in college, Chicago had one or two Mexican restaurants. That was IT in the entire city. That was a cultural shock for an Angelo, born and bred.
Nassau/Suffolk is on the safest 25 list (#16) of 330 metro areas.
Well, then learning that the area just west of Soldier Field is now all very expensive high rises, with more being built, should shock you even more.
The Hamptons are on Long Island........way, way, waaaaaaaaay out at the end of Long Island and I most assuredly know the difference between an exurb of N.Y.C, and a place at the outer edge of London proper. LOL
Nassau is a COUNTY on Long Island ( the North Shore) and is another topic altogether; Westchester is upstate. :-)