Finish the LEDs ASAP, at least all the ones you regularly use. The rate of return on those can be staggeringly high, as much as 50% in some cases.
Check your thermostat. I don't care which season it is, 68 is silly. Work on your tolerance, spend time outside, adjust clothing, etc. And *definitely* use a programmable one so the system adjusts by a few degrees while you're gone. Don't buy the old wives' tale about using more energy to bring it back up/down for your arrival. Physics says it's bullshit.
Thermal curtains would probably help with those big windows.
Consider an energy audit if you have any local programs that are free or cheap. Or just walk around and feel for hot/cold spots. It can be fairly intuitive. Look in the attic. You want well over a foot of insulation. Check doors for weather stripping, gaps, etc.
MMM has a whole blog entry on this, with some other ideas too.