Well, one problem you have is that a great many artists painted "mostly women," and this wasn't necessarily a matter of "social" or "political" meaning.
In Lautrec's case, however, it certainly was. Note that he painted women in certain types of settings: cafes, dance halls, even brothels: they were entertainers, dancers, prostitutes, sometimes just cafe and nightclub-goers. He was fascinated by the rapidly developing urban culture of 19th-century Paris, and that culture included certain types of women doing certain things that either wouldn't have been common among them earlier or wouldn't have appeared much in important art.
So, that's your "hook": what are the subjects that the artists are painting? How do Klimt's women -- and the MEANING of those women -- compare with Lautrec's? What are Klimt's women doing vs. what Lautrec's are doing, and what does each set of women represent?
Both artists are sometimes dealing with very erotic subjects, examining and presenting women in interesting new ways, but Klimt does this via symbolism and unusual allegory, a suggestion of dream imagery and inner states, while Lautrec is out and about in the city, considering actual nightlife and the way human beings are actually functioning (within the context of his unusual style, of course). Their two different approaches certainly reflect a more frank sexuality, a greater acknowledgement of women as sexual beings, and they are both influenced by 19th-century urban developments and psychology, but while their subjects may be women, the point of those subjects is different: you might call it the difference between the interior and exterior life of both men and women.
