Many times people take the designs from tribal or cultural backgrounds and interpret them to their own life and philosophy. For some time there was the trend of having Asian symbols tattooed down the back of many individuals. It then turned to Celtic designs and then there are also other symbols and languages that have been popular also. If you're looking for a design that wont lose effect, I would suggest you choose timeless tattoo designs. This way they wont go in and out of fashion, because you are going to have it long after the trend dies down.
Another thing to think about when you are looking at designs is where you plan on having the tattoo placed on your body. Some designs look better on your torso, and others are better suited to arms and legs, even feet and wrists. Good tattoo designs will compliment the placement you have chosen for it.