We have two big windows (though nowhere near as big as yours Sarah). When I took over my shop the previous owner had two massive stone urn things in them which took up loads of space so I auctioned them off and then realised why he had put them there!! In the end I put a workbench in one window so customers could see someone working close up but the other one was always a headache coming up with new ideas. About 18 months ago we had a Metz training day at the shop and the designer shifted every last stick of furniture around. We now have display tables in both windows which has doubled the display space in the shop and saves the headache of coming up with full height themed windows with props etc all the time. I haven't looked back from this, though it was a shame to loose the workbench in the window, it was fun to work there and people did stop to look at what you were up to.