I think most of the easily available monospaced serif (as you asked) typefaces have already been mentioned. One worthy typeface that hasn't yet is Gyre Cursor. Although it doesn't ship with TeX Live, it's very easy to obtain and install. I find lots of use for it in small blocks of running text, especially
\url's. It's a nicely reworked
courier drop-in (however, on that front, I'm guessing you might find it "particularly ugly" :)).
I know you asked for typefaces from the TeX Live distro, but as I have a minor love affair going right now with Adobe's
ITC American Typewriter, I can't resist mentioning this very attractive font set (see sample below), if only to provide a look at a
tt typeface that is not, to my eyes, "particularly ugly." Only for running text, however; I certainly wouldn't use it for listings.