Try Bryan Talbot's The Tale of One Bad Rat, Marjane Satrapi's Persepolis, or maybe Barbara Kesel's Meridian if she likes fantasy. I don't think women tend to enjoy superhero stuff, but if you want to test the waters, try the first couple Ultimate Spider-Man tpbs, James Robinson's Leave It to Chance (probably more of an adventure strip) or possibly Peter David and Gary Frank's Supergirl.