In the 2 models you named it does seem they only are listed in 3 sizes (Trek) or 2 sizes (Specialized). The biggest difference between the 2 it me is Trek's have a suspension for and the Specialized has a rigid fork. I would recommend the Specialized on that feature alone, I would prefer a rigid fork to a low end suspension fork. As far as your foot touching the front tire, I think that's pretty common. It's just something you learn to avoid and not let become a problem. It's something I've read was common on smaller frames but I'm 6'3", ride a 61CM road bike and a 24" MTB and have "toe overlap" on both.