I'd go for an Orange Jasmine (Murraya paniculata) with lots of lovely fragrand white blooms periodically through the year. Or maybe a Crepe Myrtle - the new series with shiny dark leaves come in a bunch of different color flowers, too. Now that I'm thinking of it, that's what I'd plant if I were going for a small tree right now.
I also grow a lot of Brugmansia, which also have beautiful, huge fragrant flowers, at about monthly intervals, and grow to large shrub or small tree size. The down side with them is that they are a hazard to small children and pets (if you have an inquisitive pet that eats plants . .
) But you certainly can prune them up so the branches wouldn't be within reach. Another note on them is that they are heavy feeders and like lots of water.
