I have often wanted a good single perl style guide -- like the MLA or something, but for perl -- but it just can't be done to enough people's satisfaction.
I personally tend to end up with lots o' parens, and if needed I break them up on multiple lines. (sometimes! i swear!)
I think this qestion is one where really, context can matter a lot. do what's right for the situation -- but if you're having to add tons of parens to clarify a precedence issue, consider making it more than one visual line, if not more than one conceptual line. yeah, your code may be a litle faster if you skip a few assignments to temp variables -- but do you care that much?