Near the top of a thread page is a tab called "Thread Tools". Click on it, and the first option is "Show Printable Version". Click on it, and you get the text of the posts without avatars, signatures, etc. Very compact! Also, in the upper right there is a link saying "Show 40 post(s) for the thread on one page." Click on it, and you have fewer pages to read through. Nice!

I don't know if the 40-per-page option is desirable for printing, since only so many lines fit on a sheet.

Thread Tools may be common knowledge here, but I just stumbled on it, and I hadn't heard it mentioned before.