Hey! i can really recommend you to read some on http://www.pfaf.org/index.php

Hope you find your answer :-)

My first choice is a perennial called Scabiosa, 'Ritz Blue' and 'Pink Mist' are small, mound forming versions with mauve and pink flowers, respectively.
Jasione is another - also low growing with lovely blue flowers.
Echinacea - taller with pinky purple flowers.
Monarda - as above.
And if you wanted a shrub, why not choose a Buddleia - there are the usual tall ones but you can now buy the newer shorter varieties too.
A lot of flowering shrubs would attract them to some extent.

In my own front garden i plant to attract butterflies and bees :-))