@jmosh - If you want to decant your wine, you really should buy a decanter. The wide bottom and open top allows the oxygen to reach all of the wine, as long as you swish it around every so often before serving.
A lot of red wines should be aged a little because of the tannins in the wine that make the flavor harsh. The flavor doesn't change exactly, it just becomes smoother and tastes the way it's meant to taste.
And some red wines that have been aged more do have sediment. These are usually the more expensive bottles. The rule of thumb is any bottle of red wine aged more than three years should be decanted.