My Pannetone is to "cakey"

Baked my first pannetone yesterday.  Rose fine, looked and tasted great but the texture was a bit to "cakey" and a little heavy.  I was expecting it to be lighter and more spongy.  After adding the fruit the dough was a bit wetter than I am used to but after the first rise it had a nice  stringy structure with lots of bubbles.  Second rise was a little slower than I thought it should be (about 3 hours).  Both rises were at 78F.  The recipe called for all purpose flour but I wonder if I should have used bread flour. 

 What else should I do to get it more spongy?