Michael of The Gardener's Eye suggested I take a look at Luciano Giubbilei's use of limbed up Parrotia perscica in his 2011 Chelsea Flower Show garden, which won a Gold award. These twisting trunks (the image is from Giubbilei's web site) read like a masterful calligraphy, and lend a sense of repose, like motion caught out of time. Giubbilei talks about the garden in this BBC interview.
I really love these, but I can't wait 40 years at my age, and I certainly can't afford such carefully grown, old trees for my Brooklyn garden.
I've considered alternatives to the now final choice of Sunburst honey locust (Gleditsia triacanthos 'Sunburst'). The native grey birch (Betula populifolia), used extensively on the High Line, was an early contender.
It's a small native tree, and its white bark would look good with a high trimmed canopy. Here it is in winter.
As used on the High Line, it's very effective in creating secluded spaces and a naturalistic feeling in an otherwise very exposed and open environment.
It's trunk is attractive and the white color would provide a dramatic contrast in a shady garden (and mine will become more shady year by year).
Even if I trim the trunks high, the clumping form of the birch may take far too much space. And the birches can't match the locusts for stunning color.
Ultimately it's a matter of personal choice, and some chance, I suppose.