Most "trees" will rapidly exceed 5-6 feet :-) You could look at dwarf conifers but they too might eventually grow larger than desired. Many retail nurseries offer what they term "patio trees", which are shrubs trained to a single trunk in a tree-like form - ninebark, willows, Rose of Sharon, various viburnums, hydrangeas and flowering currants are often offered in this form and will remain smallish.

Or you could just do a selection of smaller flowering shrubs and perennials, using the boxwood as a low border, siimilar to a knot or hedged herb garden.

What is her idea of different, specifically? Anything there, or she just knows she does not like the stuff she has now? Patio standards like those mentioned would certainly fit with the formality established by the box edging.

piet oudolf does some really fun stuff with contrasting trimmed boxwoods with wild looking perennials.

i would do a google image search of his name and see if you like the style.

Here is a link that might be useful:

I just got lost in the internets looking at Piet Outdolf's garden designs. Thanks for posting, eeldip!

"Crazy meadow looking stuff" is too transitory for me. Some nice pictures, but what did it look like last week, or next week? What kind of maintenance is involved, especially for the nongardener? Cleaning up Boxwood trimmings in a meadow doesn't look like fun.
I'm not a fan of Boxwood to begin with, so I'm writing with a prejudiced keyboard.

I agree with botann. It will be too much work to maintain.
Will look for some standards following advice of gardengal.
Thank you, people