Ok, a common problem -- a large derriere. Big butts are in, but, not everyone needs or wants to show off their booty.
Here's some styles that flatter ample rears, rather than advertising that "baby's got back!"
Skirts
Bad look for ample rears --
A-Line Skirt
Better look --
A Pencil Skirt
Another good look --
Flared Skirt
Why? An A-line skirt will bubble out over an ample behind.
A pencil skirt clings in all the right places and is well tailored.
A flared skirt will skim the butt, will come in on the legs, and kick back out again at the hem, giving a beautiful "S" shape.
Note: With this, and all entries, look at the overall style, not the one particular example. You might hate any one piece I choose, but, it's the style of the piece that is important.