Long Accurate Time Delay
The microcontroller is the way to go. Quartz crystals are known for their accuracy, but even that is relative. Standard crystals are 100 ppm, you pay extra for 20 ppm. 100 ppm doesn't sound too bad, but it's only 0.01%, and may give you an error of up to 8 seconds a day, or more than 4 minutes(!) per month. Even the 20 ppm results in an error of 2 seconds per day.  

The solution for timing long periods is to synchronize your timer to a high precision clock. DCF77 (Europe) and WWVB (North America) send a pulse every second, a timing derived from an atomic clock. You could count these second pulses for timing the longer periods and for sub-second timing rely on the crystal.  

edit
The picture shows a DCF77 receiver module by Conrad: