Btw, for rapidly prototyping iOS apps I highly recommend Balsamiq - it's amazing what you can do with that tool :)
As a side note, I also hate, hate, hate using things like Balsamiq and other wireframing/mockup tools that you use a computer for. I'm a designer first and foremost (Art degree), and if I have to see something before beginning any coding/visual design work I'll draw it out on paper first. Most of the time though, I can keep the whole visual design process of which screens go to where and how they should look in my head. I think you're also underestimating how much visual design work has to happen, including after iterating a few times on the design, after doing your mockups. A few pixel shift here and there or bumping up/down a font-size, or even changing a gray from 65% black to 63% is fairly common. So, I just skip that mockup phase and start making the thing - iterating the design all the way through.
Paper does work well for this, and you're free to not like Balsamiq.