Since it is more efficient to run the AC for longer intervals at peak efficiency, are there progammable thermostats on the market that allow you to program a gap between cooling desired temps and the temp at which I want the system to turn on. For example, I want the AC to cool to 77, but not come on again until the temp is 80? As it is, the AC is constantly cycling on and off because the there is no "buffer" range.

There are some stats with hysteresis, but they are hard to find.

The Honeywell Vision Pro series, see page 7 here: http://www.ntsupply.com/files/products/69-1896EF.pdf

Parameter 220 and 230 are cycles per hour. Changing that parameter can limit run time although you won't have precise control of the differential.

Warning - it's not a simple stat.

I have a ritetemp 6022 and it's got a swing setting that will go from .25-2 let you set how much it varies.