The two framework examples you give are not at all on the same level. CodeIgniter has a lot of stuff to structure your application, but many experienced PHP developers wouldn't bother with it (and I, personally, don't think it's worth all the extra code you're importing); web.py, on the other hand, merely gets you partway to where PHP starts, with regard to writing your application. If those were your only alternatives, then I'd say you probably want to use web.py, but if using web.py is one of the choices, then you might just as well use PHP without a framework at all, which is one less piece of third-party software to go wrong.

One thing I've really liked about PHP is that (using Apache) if the webserver is up, PHP is up. When I developed most of the applications in Python, it seemed as though I was constantly worrying about the application process failing, even though this happened very rarely.

PHP really is an ugly language, but you eventually get used to it. :(