Just for the fun of it, try out a few frames that are even further along the lines of smaller than you can imagine going -- just to see. I tried riding some bikes that seemed 'out of the question' small for me -- they were outside the framework of my assumptions, or outside the boundaries I had artificially set up in my mind. I found it very enlightening to ride these bikes, even if I settled for a bike that was one notch up in size. I never would have given them a second thought if someone hadn't steered me in that direction.

Sometimes it helps to explore the extremes, to get a better sense of what is just right.

Also, you might ask a few experieced bike shop employees what sizes they r e c o m m e n d, without influencing them one way or the other -- just ask them for their honest views on it. Then try out those sizes, and also a size up and a size down. It will help give you a better feel for the factors involved.

It takes a little variety and experience, in actual riding, to develop a feel for what really suits you best.

And remember that, at the end of the day, it is the way it actually works for you that matters most; you're the one who will be riding it. Listen to others, but in the end make the decision based on how it actually feels and fits in your own experience of it. Some bikes just feel right. You can learn to recognize this quality, but it takes some actual riding of various sizes and bikes to develop this.