Answer: It sounds like you have a beautiful setting and an excellent foundation for a "wild garden". Several tricks to enhancing a natural setting would include an analysis of the surrounding views (where to direct the eye and where to contain it) as well as creation of a focal point for the area.
Subsequent to that you will be able to incorporate a bit of structure such as paths, perhaps a seating area, and so on to both introduce some taming aspects and to make the area more enjoyable. These can be done using natural materials so that they are well integrated but also enhance the experience.
Along with this "hardscaping" you might consider adding some well chosen shrubs and/or small trees. These will help provide some height and year round interest and woody plants as a group are usually "low maintenance" compared to perennials and annuals.
You might wish to contain or limit some of the more aggressive plants that are already there. This can be done by hand eradication or by selectively using an herbicide containing glyphosate, or in some cases by repeated mulching to smother the target plant. When you do this, hoever, be prepared to replace it with something more desirable because mother nature has a way of filling in any blank space very quickly.
When selecting herbaceous plants to add, consider the microclimate and soil carefully so that you select something eminently well suited to the spot. Trial and error will also be of help in identifying plants that are able to "naturalize" there, prividing clues over time as to what to try next.
You have a wonderful opprtunity and a good start. Best of luck with your project!
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