[Edited]
Are there any fans of SourceSerifPro here? I'm using it, and am thinking it needs a little extra space between the lines than what my software selects by default (11/13.6 pt), but I don't have an eye for such things (not a designer nor a typographer).
Any advice? What seemed to look good to me was a considerable bump from 13.6 pt, which makes me hesitant. Many of the comments are of the nature of "do whatever you think best", but I doubt anyone would give such advice to an intern doing work for a paying customer. Experienced judgement has value.
I'm using this font for class handouts printed on letter paper, with a fairly wide line that averages about 80 characters per line (about 5 3/8 inches).
I've lengthened my examples and provided them in a context showing the actual width of my text block. (Unfortunately, unless your monitor is larger than mine, the site shrinks the image in order to fit it.) I also labeled them in absolute units, since that seems less confusing.