Here's a few more suggested perennial plant combos...
First, an interesting combination of Iris sibirica 'Butter and Sugar', Tradescantia 'Concord Grape', and a Rose.
Second, good ol' Veronica spicata 'Red Fox', with the newer Coreopsis 'Autumn Blush'. I have generally found the latter not to be hardy here in zone 6, and so have been somewhat disappointed, but I am however, looking forward to trying the newer varieties as they become available. You can see some here.
Finally, here's one that I've loved for several years now, Campanula 'Kent Belle' with Aruncus aethusifolius. Similar combinations could be made with variations of the above and/or Campanula 'Sarastro' (generally better than 'Kent Belle'), Aruncus dioicus, Aruncus 'Horatio', or Aruncus 'Misty Lace'.
Here's to dirt under your nails.