The Guaras here top out about 2 feet. The only combo I've like has been with large flowered Penstamons.

My butterfly whirls (white) grows to about waist high before I cut it back in mid-august because it stops blooming. It is now blooming again. I grow it in front of Japaneese silver grass and kinda mixed in with mid height cactus dahlias.

I have 1/2 a dozen good-sized clumps of Gaura Whirling Butterflies. (I originally started out with 2 plants.) WB is white with pink accents and get 3-4 ft high and arches over other plants. It is supposed to be a dwarfer version than the species ones, which may very well get 8 ft. WB start blooming pretty late for me and just about everything has had its first big flush before they start. There is still some bloom today!

Mine are planted with daylilies (mostly in the pink range)& hardy lilies (whites, pinks, and whites with pink/red markings - I always plant Asian with later varieties in the same color range), purple coneflowers & various phlox in colors from white to pink to red, backed by foxgloves (in a bit more shade)followed by asters and mums.

The small flowers are a good contrast with the larger blossoms of daylilies and hardy lilies, and the heavier looking coneflowers, phlox and foxgloves. They also add movement to the other stiffer flowers.

WB will overlap the daylilies some (esp. reblooming ones) follow the Asian lilies, but surround & soften their stalks, be in partial bloom with some of the coneflowers (I have 3 kinds) be in full bloom with oriental lilies and finish with the asters and mums.

It's a great plant and works well with lots of things. It can also handle some of the dampness that is liked by some of the other plants I mentioned even though it is taprooted and quite drought tolerant. Enjoy!

P.S. Despite what I have read about Gaurga being hard to move or split, I have had no problems at all.