If you visit here regularly, you know that I love my step-through frame bicycles. They are so easy to hop on and off, in almost any type of skirt or dress. You can just swing your leg through the frame as you approach a driveway, tapping the brakes so that just as you leave the road, your feet are on the ground and the bike is stopped beside you. Graceful. Elegant. Exactly what you want in a city or city-country bicycle where you make shorter trips, wear fashionable outfits, and dismount fairly often.
However, these frames are not suited for all purposes. For off-road riding or carrying lots of gear on a long trip - as in touring or bicycle camping - it can be more practical to use a frame where the top tube is closer to horizontal. This is properly referred to as a diamond frame. The name references the diamond-ish shape created by the forward (headtube to seatpost) and rear (seatpost to rear hub) triangles of the frame itself. See Velouria's guide to classic bicycle frames if you want a visual. This design is remarkably stable. It can even make it easier to carry over obstacles, if you're going on that sort of trip. And for long inter-city rides, you are interested in comfort and efficiency of effort, and less interested in ease of dismounting.
Now there are plenty of touring bikes with step-through frames. Nearly every European manufacturer offers some touring and trekking bikes, and they almost all come in "men's" and "women's" versions. I have no idea how this affects their handling. Nonetheless, when I was looking to get a spare bicycle to leave at The Beau's house, I went for a diamond frame. It seemed to make sense to add some variation to my collection of bicycles. However, I have not used it for touring yet, nor finished setting it up. I don't even have a rack on it yet, which has led to some severe pouting as I try to stuff everything into my purse or hang it on the handlebars.
I also keep showing up in a skirt, and I have had to get the hang of mounting and dismounting without being arrested for indecent exposure. After several tries, I think I have the hang of it. As I read somewhere (bikeskirt, perhaps?), the trick is to kind of kick yourself in the butt while sliding your knee modestly over the top tube. Tilting the bicycle over a bit helps too. And riding is riding...I was in my corduroy pencil skirt with the deep front slit last weekend, one of my most difficult skirts. Hard to even sit in a chair without showing too much. It performed surprisingly well. My stretchy black skirt was a breeze this weekend. New tricks!