As far as health is concerned, I feel fine at the weight I am now (170 lbs).
As far as vanity is concerned, I'd like to lose a bit more, but not much. I think it all depends on your skeletal frame. I have a wide pelvic girdle, which is already beginning to show through the skin - a look which I don't like (though others may!). Also, my rib cage finishes just 1 or 2cm above my hips, so I'm never going to have a small waist - there isn't enough space between my ribs and hips for my waist to go in.
I'd like to achieve the magical BMI of 25, but as soon as my face starts to look drawn or saggy, I'm stopping!