From which part of your house (which windows?) do you plant to view your wannabe japanese garden? It's not clear from the photos.

I am interested in the views from the sunroom looking out to the back yard, the kitchen window (not shown), my office window - it currently has a whiskey barrel and lantana planted, and the guest bedroom which looks out on the front yard (as does my office).
It doesn't show (it's too small now) but I have planted a willow at the farthest point of the back yard. I want to preserve the view from the back door (sunroom) so that the willow will be the backdrop for the rest of the yard. I would like to plan more sitting areas in the yard as I spend most of my liesure time outside.
Also, the stuff sitting outside the door of the sunroom is going to be replaced as it looks to junky - as does the vegetabe garden. It is being moved to the large black containers which are hidden behind my husbands shop.

How about some photos of those windows and from those windows?

First off do plan your garden fo the views from your house. Western gardens often go for views from afar but Japanese focus on looking out.

Keep the mature trees you have but consider a pond. You have alot of land and water should feature - even if it's a dry pond! A teahouse may give a focus and destination but plan how you might walk around the garden. Try to have a bridge crossing the pond and plenty of rocks, possibly suggesting a mound the waterfall drops from (good use for soil removed from pond).

Cytania, thanks for the ideas - that gives me some idea of how to start thinking about my garden plan.