Road bike with drop bars, or mustache bars. Really important because you will want to change hand positions frequently. Then you really want a pair of padded gloves that fit perfectly and don't have too much padding.
http://www.sheldonbrown.com/deakins/handlebars.html
Seat or Saddle. This is the number 1 complaint, and should be installed and ridden right now to get used to it and see if it fits. The best option is to find a shop that will help you trade your new saddle or seat back until you find one for sure that fits.
There really is only one or two Saddle manufactures and Brooks is the one you have probably heard about. Full leather, needs care from rain and theft, but the most comfortable!
http://www.brooksengland.com/en/Shop_ProductPage.aspx?cat=saddles+-+touring+%26+trekking&prod=B17+S+Select
http://www.brooksengland.com/en/Shop_ProductPage.aspx?cat=saddles+-+touring+%26+trekking&prod=B17+S+Imperial
Everything else is a seat, that is why they sit on a seat post. (my own analogy) The most famous womens seat is made by Terry...
The Liberator seems to be the one that works most often for most women.
http://www.terrybicycles.com/Saddles/Womens-Endurance
Another option that also works really well for others I know are made by Planet Bike,
http://ecom1.planetbike.com/5001.html
Along with that seat/saddle, you will really want good quality bike shorts, loose fitting if you prefer, but definitely seamless padding.
The next super important bike item is shoes.
Stiff soles greatly reduce tired feet, and transfer power more efficiently. On long tours you really want this. Even a good fitting cross training or casual/recreational cycling shoe is going to be much better than street shoes of any kind except maybe Dansko clogs with solid soles...
Clipped on to clipless pedals as a system, is the most efficient, and only takes a few rides to learn how to clip in and out safely and efficiently. Once clipped in, you can then learn to pedal smooth efficient circles, and apply power 360 degrees (in theory but takes practice) of pedaling.
Pedal example
Shoe example
Hands, Feet, and Seat are all points of contact with the bike, and you really need to address all 3 of these areas with equal concern and attention to assure a comfortable and enjoyable ride that will be fun and encourage you do keep it up.