variegated ginkgo ...it will be decades before it outgrows the spot....

just about anything else.. will outgrow that space in 5 to 10 years .. nothing stops growing.. at the 'size estimate'

ken

Here is a link that might be useful: link

Just looking at the picture I am thinking something with bold foliage- first thought to my head was Cotinus 'Golden Spirit' AKA Golden Spirit Smokebush. Brilliant yellow leaves that will hold their color well (given enough moisture) and can have great fall color too. You could use it as a cut-back shrub to produce bigger, showier foliage each season. Can easily be kept at around a 6' height. Also can be had for a reasonable price.

In my area weeping cherries are subject to much disease/ Japanese Beetles, and weeping mulberries are something everyone has.

I've used the newer weeping river birch 'Summer Cascade' and have been happy with it- good foliage, fall color, and bark/branch effect during the winter. Of course as Ken stated in time even small trees might get wider than you would like them to. There are a couple newer weeping redbuds that might fit your bill too- Whitewater or Ruby Falls. Maybe would be a couple smaller Japanese Maples that will work too- but I don't know the best varieties.

Overall I would go for something gold, red, or variegated- if it will be surrounded by boxwoods you need something that will stand out against them all season.

Good luck,
Bruce

Thanks, guys. Those are some great suggestions! I will avoid weeping cherries and mulberries.