My past partners have ranged from 12 years younger (nothing like that, she was at University) to 91/2 years older, from very pretty to chewing-a-wasp level of attractiveness, from four-rolls-of-tummy-fat to dances-on-a-podium-in-a-club-athletic-slim. Hair skin and eye colour have all varied.
I think the thing is SHAPE, not weight. Well, by 'think', I mean my personal taste agrees with much of the research I've read.
If your waist is around 0.7 the measurement of your hips (the WHR), you will look attractive to most hetro men. This pattern is kept throughout the world, whether the cutural prefence is for ectomorphs, endomorphs or mesomorphs apart from some primative hunter-gatherer cultures. Here's a rather cheesy photo I found that some researchers morphed as an illustration.
Essentially curves rule. I like lithe and slim - not boney and skinny - but I only like it if there's curves. I also like well-padded (say top end of healthy weight range) - but I only like it if there's curves.
And, unsurprisingly, curves are a good indicator of general fertiltiy; if you've got an hour-glass shape you're less likely to have problems conceiving than if you're straight up and down.
What I don't like is huge boobs. I am happy there are millions of guys who LOVE them. But I'm not one. B cups can reach a perfection of shape and position that only the most exceptional D cups can... and the B cups will still be in the same place in thirty years time...
Of course, we could get really un PC and talk about whether sexual rsponsiveness and weight are connected...
What about the ladies, is it weight, or that triangle shape (wide shoulders, slim hips) that get's your motor running?