I'm a 5'6" woman with a 29" inseam, so I ride a relatively small bike for my height. 43cm/17" Breezer Villager. While I *can* ride a size larger in a step through, it ends up having the feel of a Cadillac instead of a bike. Most people can ride 2, sometimes 3 different size bikes, and what suits depends partly on personal taste, and partly on how you're built.

You can ride in a short skirt on a diamond frame. If you're on a derailler equipped bike, you can do certain things to keep your pants out of the chain (like install a ring guard). So what I'd do is test ride, and not just bikes that you like the looks of. I've test ridden an Electra Townie, and it's a nice enough bike. But it doesn't fit me, and the shop staff and I couldn't come up with any way to *make* it fit. Two of my friends just got Townies and love 'em. Batavus is easy to get locally, but I can't lift the step through... which is kind of a problem when you need to get the bike into and out of basement storage.

You'll have a lot clearer idea of what you need and how much it costs the more you ride. Not just test rides, but just using a bike to do what you want. My Villager is my second bike, and while it's not perfect, getting to my idea of absolute perfection would be a good $3000. The first bike was a $350 mountain bike that I rode the hell out of... didn't fit very well, was built to be reasonably aggressive on dirt trails (which is kinda crappy on a paved road), but it got me places. After a year on it, I had a very clear list of must haves, and it was easy for shops to help me find the right bike.