Now that the button icons have been removed :
http://bugzilla.gnome.org/show_bug.cgi?id=583352 , 

Plain text button isnt very visually stimulating, 
I suggest using color hints for buttons with only text [icons optional via gconf if needed]
ex:a hint of green for affirmative actions , save , etc...
 a hint of red for delete , cancel , abort , etc...

This is just a basic idea , rules for the colors need to be explored further.

Something in the buttons themselves , to be more visually stimulating and the
actions instantly recognizable, than having to read the buttons to recognize them.

This would make the dialogue windows be less monotonous.