I try to add rock garden perennials to the beds in close association with the succulents. For instance, I experiment repeatedly with penstemons, only a few of which have succeeded long term.

Townsendia, evergreen Rocky Mt. wildflowers
Planted in pumice-sand-gravel mix

Full sun, good drainage, undemanding.

Bletilla striata is everyman's orchid
sun or shade easy to grow and tough

Ordinary garden soil and mulch in zone 6. 

Helianthemum with Jasminum stephanense
The Jasmine is a good zone 6. The sunrose is a cute rock garden evergreen

This Jasmine is a hybrid of  J. beesianum and J. officinale. It has little fragrance but is an aggresive grower. Plants at my old growing grounds in Dayton Md have survived  -16F and 24 hours below zero.

Daleas,leguminous herbs & shrubs from the SW
The plant is spare and the flowers small, but really interesting close up

Small Daleas require sharp drainage and hot sun. They leaf out late and are often short lived. The cactus in the upper right corner is Opuntia imbricata, cholla.