I don't know where you're located, but if you can get to Blue Moon Gardens in Chandler, they usually have sweet olives. (I'd call in advance if you're traveling, although the nursery is worth the trip if you're anywhere in north Texas.) You can also see (smell?) their full-size one that's planted on the north side of one of their buildings.

Magnolias are gorgeous with big white flowers they look very tropical. They are large trees but if you keep pruning them they will stay as high as you will allow them to grow. I have seen them in another garden so we are trying it in ours

All trees drop their leaves - the only difference is when, and whether it's all at one time. I have a huge wisteria which drops an enormous quantity of leaves onto a paved area in autumn. I HATE sweeping. So the leaves are left until they have all fallen and then get cleaned up in one foul sweep and put onto the garden. Wouldn't suit a lot of people (like my friend who regularly washes her front fence) but gardening is such a personal thing. From the sound of things, you are only going to have one tree. Make it a tree that you are going to be happy to have and happy to live with. Forget the evergreen ash. How about taking a walk through your botanical gardens and similar places and looking for "your" tree. Council parks and streetscapes, as well as leafy suburbs will also provide examples. If staff or owners don't know what the tree is, ask permission to obtain a piece and take to a nursery for identification.

Patio was like that when we moved in, we used the gravel/stepping stone area for potted plants, a grill, and the chiminea, and I am not in love with it. Part of the plan is to make the gravel area smaller or change it to all flat stone and extend the flower bed and mulch where the grassy section will be within the treeline or fence. we are allowed privacy fence here but it can not be taller than 6 feet and it has to be white vinyl, we can't plant between the houses on the sides and trees need to be at least 5 feet from the property line. Just not sure if fencing is too much for the area, I don't mind being enclosed but will it look out of place ?