We installed programmable timers on both our electric water heaters per instructions at this website:
http://waterheatertimer.org/
Its my wife, me, and two teenage sons. We've had little problem with dealing with cold water showers. The water in the insulated tank stays pretty warm so it only takes about 30 minutes to come to full temp after the heater has been off for 8 hours or so.
Water heater timers, and HVAC setback thermostats save energy because the amount of temp difference is what drives heat transfer. This effect has been well documented experimentally by work done at Oak Ridge National Laboratories and other places.
We've had real good luck with our setup. The guy who put together the website above did a real good job.
Cheers.