I just finished Wilkie Collin's "Woman in White" and I am absolutely fiending for some gothic 19th century atmospheric novels, hopefully with women protagonists...anything you guys can recommend?

Don't remember the exact century of this story, but you might try Steven Brust's Freedom and Necessity. Co written with Emma Bull. I liked it a lot. They wrote it a lot like it reads. By writing letters back and forth to each other.

Sample chapters:
http://www.tor.com/sampleFandN.html

These are pretty much the standards of early European Gothic fiction:

The Monk by Matthew Lewis -- usually conisdered the first Gothic novel, it's a fun romp involving the devil, the church, and all kinds of intrigue, including sexual overtones more graphic and shocking than in the novels that followed.

The Mysteries of Udolpho, The Italian, and The Romance of the Forest by Ann Radcliffe -- Radcliffe pretty much created the mold that everyone else then borrowed. I've only read Udolpho, but it sounds like it would be right up your alley. Radcliffe is easily the most important and most oft-imitated Gothic novelist.

The Castle of Otronto by Horace Walpole -- Very much in the Radcliffe vein.

Northanger Abbey by Jane Austen -- actually a bit of a satire of Ann Radcliffe, it's a fun read.

Also, since you liked The Woman in White so much, pick up The Moonstone, also by Collins. I've never read it, but its reputed to be as good as or better than The Woman in White. EDIT: Now that I think about it, I believe The Moonstone is more of a detective novel (and a very early one at that) than Gothic.

And, of course, if you've never actually read Bram Stoker's Dracula and Mary Shelley's Frankenstein, you should. Dracula, the novel, is so much better than I had expected. I taught it once in a freshman comp course and had a great response.