So, I've made several loaves of sourdough from my starter, and the flavor is all there.  Sometimes a little less sour than I would like, but usually all there.  So far, I have just been making a very basic bread (KAF White Wheat, starter, water, salt), and have sometimes branched out to adding some rye flour into the final loaf, but nothing more exciting than that.

I let my sponge sit overnight in the over with the light on, and it rises up nicely.  The next day, I build up the final dough, let that rise until it is doubled (an hour or two) while I go to the gym.  When I get back, I punch the dough down, knead it some more, shape into a ball, and let it rest half an hour.  Then I punch it down, shape again, and let it sit another half hour.  Then I divide in two loaves, shape and stick in the respective proofing containers and let rise about an our.

I proof my boules in a banneton, and my loaves, I proof in a clay baking dish.

About half an hour before baking, I soak my baking stone for 15 minutes, stick the stone in the oven, and start the preheating to 450.

I then turn the boule onto the stone, give it a slash, and stick the clay pan beside that, after giving that a couple slashes.

The end result of this longwinded yammering is that I have a very dense loaf, with a very stiff crust, that has a nice tang to it.  I'd like to lighten this a bit, and get more of those nice air pockets.  I'd also like to get the crust more crisp than hard.  Thinking if I knead longer, and maybe add some more water for a wetter dough, I'll get those air pockets, and, if I add some fat, I'll get that crispy crust.  Can anybody confirm/refute that, or offer other advice?  More important to me is getting that nicer crumb than what I have, at present.

Thanks!