For toughness and drought tolerance I nominate Cornus alba 'Argenteo-marginata'.

After two seasons of watering in times of stress this plant can be left to defend for itself. The variagation stands out well against a dark background.

I like to use it to separate holly from Hydrangea.

In late winter it can be cut to the ground after a slight show of growth.

Variegated Japanese Kerria. Nice green stems in the winter. Delicate bright yellow flowers in spring and green and white variegated foliage all summer. It will grow in sun to shade, preferring partial shade. Easy to grow.

Osmanthus heterophyllus variegata, known as False Holly. Evergreen with small glossy-leathery holly-like leaves edged creamy-white, tinted pink when young. Mine is 8 feet tall, kept slender by pruning for vase use. It is growing in a large clay container with morning sun, with a variegated Carex morrowii swirling at its feet. Hardy to zone 7.

I have a smaller O.h.'Goshiki', and it's a little more flecked and streaked with cream & yellow...I haven't quite decided if I like it. It's a little gaudy, not as cleanly delineated (if that makes sense). jo

I'm thinking of underplanting a autumn clematis with "Brise d'Anjou" Jacobs Ladder. Varigated gold and green; has anyone had experience with this?