Check out this link. http://english.stackexchange.com/questions/52091/comma-after-introductory-phrases.
– ScotMDec 19 '14 at 22:49
If you are looking for more subtle advice on style, consider this link
http://www.amamanualofstyle.com/view/10.1093/jama/9780195176339.001.0001/med-9780195176339-div2-293
I would probably write that sentence, "So then, what could be more wonderful than to have a faithful friend?"
It looks acceptable to me with or without the commas. There is a modern trend towards light punctuation (which would suggest no commas), but there is also a trend towards the inclusion of commas, where they are not necessary to disambiguate grammatical structures or to make long sentences easier to comprehend, for the sole purpose of indicating pauses when reading out (for emphasis / to indicate thought etc).
– Edwin AshworthDec 20 '14 at 00:00
I would probably write that sentence, "So then, what could be more wonderful than to have a faithful friend?"
– ScotM Dec 19 '14 at 22:50