For those with changing schedules, I highly suggest a wifi thermostat. You can connect to it via a computer or smart phone and change your temperature remotely. They aren't that much more expensive than a 7 day programmable thermostat either. I recently picked one up for $80 (not a sale price). I did a write up on EcoRenovator on the options and my purchase, install, and usage.
wifi thermostat options:
Internet / wifi thermostats - EcoRenovator
install and review:
Motison CyberStat CY1201 WiFi thermostat installation & review - EcoRenovator