I'm a huge fan of American yellowwood (Cladrastis kentuckea). A US native with smooth silvery bark like a beach, lovely yellow fall color, and right now, this:
Mr. McGregor's Daughter just posted pictures of her tree, and they look pretty sad. I'm not sure what the difference is: She's in Northern Illinois, I'm in Central Michigan, both zone 5. Here the show tends to be this impressive every other year, but she says her's hasn't flower in 5 years! This particular tree is sheltered by a big building, but there are lots of them around campus, and they all look amazing. Any theories?