I tried a few grids after David OK'd the theme set. This one gave me the best fill. Stacking theme answers has bailed me out quite a few times, especially when the overlapping letter count is fewer than six letters. Thanks for the new title, David!
Four long theme entries plus a 15-letter reveal is already very impressive. Squeezing in four juicy long down entries on top of all of that? Um, yes please! So how did Zhouqin do that? Her tremendous construction skills aside, she brings up an astute point about stacking theme entries in her blurb. Having three (rather than the usual two) rows in between the central grid-spanner and the nearest theme entry allows the middle section to be much more flexible. The theme entries also overlap in just two sections, so from a fill perspective, all other parts of the grid fall into place like you're working with just three theme entries. Very clever on Zhouqin's part!