Good point that would make SS have a more classic Zelda feel to it since in addition to OoT and TP, LoZ has 9 dungeons also. I was just guessing about five because I keep hearing how it is going to have fewer dungeons, but more to them or something along those lines.
I think about five main dungeons would be good. There should also be some side mini-dungeons as well.
*edit* Aero_Dynamic, now that I think of it 10 dungeons would be amazing.