Richard: BTW, the programming stems from the development of the technology (lack of processing power and memory) and has, unfortunately, now been embedded by regulation. Energy Star, subsidies and publicity are all oriented towards thermostats with “four programmable periods per day”, rather than something more interesting. We’ll see if we can break that trend.
As for the famous round Honeywell, it sure is a classic. Watch out for old ones that contained mercury. New ones have bimetallic switches. Electronic thermostats have the advantage of more precise temperature control (+/- .5 C versus +/- 2-3 C with bimetallic switches). The programming is more difficult to judge. A lot like with cars (your milage may vary), the results of programming have been mixed. It really depends on the schedule of the user, there ability to program it and other factors in the ventilation system.