Specifically LOTR is not displaying its subtitles for elvish spoken lines (WMP displays them fine) and District 9 has a lot of alien spoken lines that VLC is not displaying the subtitles for (again WMP works fine).
Fairly sure this is a general problem to VLC DVD playing as the only options are subtitles tracks or disable. Which is not the complete picture as many DVDs are expecting their subtitles to be displayed for non-english lines. Please add another subtitles option for these untracked subs.