I just moved recently from a location close to San Jose to one closer to San Francisco. Although our climate still more closely resembles that of San Jose than San Francisco, it's slightly moderated in ways that can make a big difference. It's a few degrees cooler in the summer, and frosts are fewer and less severe. We are on the boundary between zone 9b and 10a, with an average extreme low of 29.6. Jade plants grow big here. And Brugmansias can grow into small trees. I suspect they can still freeze to the ground in an unusually cold winter, but it's much less frequent.

I don't really have room to grow a Brugmansia as a tree, but my sister does. I'm toying with the idea of surprising her with a Brugmansia that she could choose to grow big (or otherwise grow in a pot).

I'm curious what species or hybrids you would pick to grow into a tree and why. We should be able to grow pretty much anything, although the climate is not perfect for species such as B. sanguinea and B. vulcanicola. I'm pretty sure they will resent the summer heat (our average high is about 75) and stop blooming for a while. My sister does not like all yellow or all red flowers.

My simplest choices would be to either root a cutting off my small B. sanguinea or to pick up a B. arborea seedling at Annie's Annuals at some point. Are there hybrids that might be particularly stunning due to their flowers, floriferousness, shape or vigor of the tree? Any photos of examples would be welcomed.
I was prompted to ask after noticing this guy a block away blooming so nicely:

This was in Spring, in Palo Alto, a few miles away. They get more extreme temps than we do, and a B. sanguinea is going strong:

Also a block away there used to be a huge Iochroma, until it was removed to demolish a house:

Here's the little B. sanguinea I have, blooming in May. It was sold to me as the 'Pasachoa' clone. It got pretty buggy (notice the whiteflies) perhaps due to the heat, perhaps the small pot. It has since been cut back and repotted: