Voltage ratings of capacitors: ceramic vs electrolytic
You do not have the same lifespan issues with ceramic caps. You will lose 
capacitance as the voltage increases. The amount you lose is dependant
on the dielectric.

When choosing the electrolytics you also need to look at the ESR, temperature
rating and the maximum operating temperature. Since the lifetime is predicted
using the Arrhenius activation energy law running using a 105°C rated
cap will give you a significant increase over running a 85°C cap (assuming
all other conditions are the same). There are some 5000 hour rated electrolytics.