Dan - both options seem to have merits.  The ground level one sounds great.
Have you considered a sun shade for a hive on the roof to shield it during
the afternoon?  If it requires a ladder, I would say forget it.
Another important factor is to have a source of water close-by.  I use a half
whiskey barrel which also holds a water lily, water sprite, and a few
goldfish.  A hive can use several liters on warm days for cooling and diluting
honey to feed larvae.  Without a closeby source the bees might bother some
neighbor's swimming pool or dog dish or leaky hose faucet.  A bucket with ca. 20
old corks floating in it as bee preservers works fine also.
I live in suburbia, but on a 2 acre lot.  I have never had a problem with
kids, but my colonies are fenced off.  I don't lose sleep over worrying
about rare instances.  As was mentioned earlier, you want the hive to be
where you can easily watch it, because you will want to, say, with a cup of
coffee in the morning.  Keep adequate space behind it for working the bees.
Wayne Esaias, in Howard County, Maryland