#3
do you mean what brands?

there are some 1 11/16 inch and some 1 3/4 inch, steel strings, generally

classical is usually 2 inch
Last edited by mizxou at Apr 24, 2011,
#4
Many makers put out a line of guitars with wider-than-usual nuts (and fretboard overall). These are generally marketed as "fingerstyle" instruments as lots of fingerstyle artists prefer a wider neck.
There is no standard; each manufacturer decides what they will use depending on customer satisfaction.
And many fingerstyle players like narrow necks as well... It's entirely a matter of personal preference.
Also there may be physical considerations. If a player has exceptionally thick fingers a wider neck may be more comfortable to play.