Roy, Thank for the comments on my Tu-22M3. I was curious for your B-17 so I desides to visit your page! The model looks quite nice already, but there is almost always room for improvement. Here are some tips to improve your model. I know you are currently rebuilding it...
First, try printing a 3 view of the B-17 on the exact measurements of the scale you want to build it. For instance you want to build on 1/30 scale and the length of the plane is 15 meters and the wingspan is 30 meter: 15/30 is 0.5 which is 50 centimeters and 30/30 is 1 meter (sorry I'm dutch so I use centimeters and meters instead of inches and feet). Try to print a side view, front view and top view of the model with those measurements. You can now start measuring by using your bricks to get a good idea as to how wide and long the parts of the plane are. That should make the designing and building in LDD more accurate!
Second, use bricks with certain characteristics for certain surfaces. For instance, use the wedge plates for the wings and curved slopes for the fuselage. This should make the model not only more accurate but also more 'sleek'. Those parts add a nice and clean touch instead of the more common, angular bricks.
Third, after you've finished the rough shape of the model (wings, fuselage, tail, etc) try adding as much little details like air vents, turrets, a bomb bay with bomb bay doors and bombs, an accurate undercarriage, antenna's etc. Those little things add much more detail to your model and therefore make it much more interesting to look at!
I hope I could be of some help with these tips! Good luck with the model. I'm curious for the result!