Here is the deal: Anywhere you put a pattern or some sort of embellishment that is automatically going to be the first thing that other people focus on when they look at you. This can be great, because you can use it to point out your favorite features about your body and it can be NOT so great, if you are pointing the thing you hate the most. For example if you always have hated your "thunder thighs" you maybe don't want to call attention to them. (Full disclaimer my legs have always been one of my least favorite parts... we all have them).
Think of patterns as a magnifying glass. So if a pattern is a magnifying glass, make sure you are magnifying the thing you want people to notice about you. If you are larger on the top and smaller on the bottom, a patterned pant may be a nice way to visually even yourself out. But if you are more of a pear shape ie. you are larger on the bottom than the top you should be really careful with patterns and choose something smaller in scale.
My golden rules for wearing a pattern on the bottom is that they should be less than 2 colors AND be age appropriate. I may be talking to you, adults wearing cartoon characters... They are totally fun for at home, knock yourself out, but unless you work at a daycare center (and even then thats iffy) pattens should reflect that you are an adult, not that you like Bart Simpson, or Ice Cream.