Take Hugh Grant. I don't find him attractive at all out of a movie - and he definitely doesn't have a great bod. BUT stick him into a romance and, yep, he's won me over. Think Notting Hill/Love Actually/4 Weddings and a Funeral.
In fact it didn't really occur to me until I sat down and thought about it, but in a lot of the great romance movies out there, you really don't see a lot of flesh. The heroes in many of these use the character's inherent traits and the romance to win over the audience. Of course, the leading men are never ugly - although not neccessarily handsome in the traditional sense, eg Owen Wilson (Wedding Crashers).
A lot of period romances have the heroes dressed in layers of clothes, and yet you still fall for the leads as much as if they were flashing their abs. And of course, this gives me a chance to include a little Hugh - the Aussie one ;o) (Kate and Leopold).
I think in developing my heroes, I pick a leading man who has played a character that has elements of my hero. I have a hero based on Gerard Butler - thanks to PS I Love You - probably the most romantic movies I have ever seen. I would never have used him as my leading man if it hadn't been for his character in that movie.
Movies keep my heroes ageless. Wouldn't take a second look at Michael Douglas, but what a hero he made in the Romancing the Stone/Jewel of the Nile flicks.
Well, I think you get my drift. So to finish off I thought I would leave you with a collection of my favourite leading men. (Pierce, Hugh and Colin)