I don't pay too much attention to school rankings, but maybe that's because I send my kids to Albany Public Schools
. That said, Niskayuna and Bethlehem both have very strong reputations. North Colonie is also well-respected, but doesn't seem to get their name out there as much, so people don't know as much about it.
I work with a lot of people who sent their kids to Niskayuna, and they have had mostly good experiences. The experiences of people whose children were strong students were much better than those whose children were average or struggling academically. All the parents tended to agree that academically talented and motivated students were treated the best at Niskayuna.
I also know a lot of people with students in Bethlehem schools, but most of them have not yet reached high school. From their talk, there seems to be more problems with cliques and drugs in Bethlehem than in Niskayuna, but there are many different strong academic options at Bethlehem High School.
Niskayuna and Bethlehem skew towards the upper middle class. Niskayuna is somewhat more diverse racially because of the presence of GE and its international staff. Bethlehem is more of the doctors, lawyers, and state workers.
Both Niskayuna and Bethlehem have a variety of housing options, from older homes in established, walkable neighborhoods to mid-century subdivisions to new McMansion communities. Parts of the Bethlehem school district are even semi-rural.
I'm not sure where you are moving from. If it is a big city, then you may find any of the communities within the Troy-Albany-Schenectady-Saratoga area to have easy access to the airport. There is little traffic here, except on certain roads at certain times, and the airport is a joy to deal with compared to those in other places I've lived. The Park 'n' Fly is a great option and about the same price as airport parking. If you want to live really close to the airport, then Latham/Colonie is best, but anywhere near Routes 90 or 87 within the Capital District - especially within Albany County -will give you quick access to the airport.