Whether you're a younger investor pursuing the next great growth opportunity or a more experienced one whose selection of stocks tends to be less aggressive, every investor's portfolio should have a niche carved out for more-conservative options.Here are three starkly different opportunities -- Aqua America (NYSE: WTR), Franco-Nevada Corp. (NYSE: FNV), and Ecolab (NYSE: ECL) -- that could help investors avoid tossing and turning all night.Image source: Getty Images.Continue reading