Yes, target weight can be tricky. You've already been given some great insight by others, but I would like to add that this thread: Using BF% as goal was helpful to me in determining goal weight. I realized my original goal of 125 would have been dependent on a loss of lean body mass. Knowing what your lean body mass is will give you a good idea of the range you would want to fall in. Knowing your body fat percentage would let you tone up and feel good without worrying about the actual numbers on the scale.

Hope that helps.