I have a wooded area at the top of my garden, with hazel, holly and a big ceanothus. There's a gap, with scratty grass and wild flowers, and then a rose arch between the wooded bit and the rest of the garden. I want to put another tree in the gap, but I don't want something that's going to grow enormous, like another hazel, and I would like something that flowers, to contrast with the ceanothus, and ideally I'd like it to smell nice as well! Any ideas?