I tried a recipe this weekend, from cake central, and it did not turn out as expected.  It held up well considering humidity in FL, but it was gritty and too sweet.  I am used to working with fondant and want to be as comfortable with icing.  My search is on for a stable, whipped, fluffy icing that doesn't taste like a vat of sugar. Any thoughts, advice would be great.

Here is a high humidity buttercream. I personally haven't tried it though. http://cakecentral.com/a/high-humidity-buttercream

I live in Florida and I haven't had much problem with my frosting thus far. To get mine fluffy I just leave it mixing for a bit after everything is incorporated. It fluffs up nicely. And I add lemon juice to cut the sweetness a bit. About 1 tsp. Not enough to taste like lemon but just enough to balance out the sweetness. Also, they make high ratio shortening that makes it a bit more stable in heat.