Tom Robbins is an entertaining and creative writer, and yes, he does feature strong, somewhat flawed women. To nitpick a bit: he doesn't understand women as well as he thinks he does. Every few pages or so, there's something that makes me roll my eyes (me and the several other women I've compared notes with, anyway). He seems to write about his ideal woman, rather than a real one. Still a good read, though.
Khaled Hosseini's A Thousand Splendid Suns
was hella impressive. Again, he gets some details wrong, but it was a very engaging book with two interesting (and flawed) female main characters.
The hands-down most accurate male writer of women that I've encountered was Wally Lamb. She's Come Undone
was a very difficult read for me (and for at least one other woman of my acquaintance), hitting home in too many ways. Lamb's central character is very real, very believable, very female, and very troubled. I had a hard time believing that the author was really a man, since he hit so many nails square on the head. It would be interesting ...
... (several minutes and a couple of Wiki links later) ...
... to find that interview with Lamb
that I just found, where he says this: "I was the only boy in our household and lived on a street full of girls, so I was the odd-kid-out." So he got to know women pretty well, then. It shows.