The G in Libertine stands for the Graphite font engine that makes all the extra features available. The regular Libertine O font doesn't have these features (or if it does, I haven't figured out how to access them).
If you have the Libertine G font, then to gain the features, you add codes to the end of the font name in the font selection box. I do this at the level of "Tools/Options/LibreOffice Writer/Basic Fonts"
For example, mine looks like this:
Linux Libertine G:onum=1&lith=0&itlc=1&thou=0&pnum=1&ss04=1&ss05=1&litt=0&hang=1
The codes mean the following:
"onum=1" -- Turn on old style numbering
"lith=0" -- Turn off the "Th" ligature
"itlc=1" -- fixes the spacing around italics words.
"thou=0" -- Don't place an extra space between every third 0 in long numbers, 00 000
"pnum=1" -- Turn on proportionally spaced numbering.
"ss04" -- Turn on stylistic alternatives (This one provides a really cool ampersand (&))
"ss05" -- Turn on stylistic alternatives (This one provides a Garamond style upper case W)
"litt=0" -- Allows the splitting of double "t" ligatures "tt" for hyphenation at the end of the line.
"hang=1" -- Turn on hanging punctuation. This gives justified margins a really nice professional look. Don't bother if your margins aren't justified.
All of the codes can be found at http://www.numbertext.org/linux/fontfeatures.pdf.
Sometimes, you want to apply a specific effect to a word or two, such as applying true small caps. It can be a pain to type in the code, so there is a Typographic Toolbar extension available that places a toolbar on your screen that makes the effects available with a point and click. The extension is available at:
http://extensions.libreoffice.org/extension-center/typography-toolbar
At the end of the toolbar is a help button that links back to the "fontfeatures.pdf" site for easy reference.
If you don't have the Linux Biolinum G fonts, I highly recommend getting them. They can be found at:
http://www.numbertext.org/linux/
I tend to use Libertine for documents that need a professional look. I avoid Times like the plague as it wasn't intended for long-term use. It's letters are condensed, which provides for "economy of space" in newspapers, for which it was designed, but you will rarely, if ever, find it used in book length works. Libertine is nice as it has the same general shape as Times, so it doesn't stand out as being too different, but it's not as condensed, making it very readable. I usually set it at 12 points, which is nice on a letter sized paper document.
You might also check out http://toolbox.rutgers.edu/~hedrick/typography/typography.janson-syntax.107514.pdf. It's a nice article summarizing a lot of the details in Bringhurst's book.
Good luck with your thesis.
Virgil