With the honeysuckles really taking off this year I love the combination of golden orange with the deep pink Betty Prior roses.
Green always sets off red, especially with these Olympiad roses.
Yellow and yellow work nicely with the Golden Showers climbing rose.
Take white, a bit of pink with a deep green background and it creates a lovely combination with this peony. 
Any color of rose goes well with McDuff, especially these early blossoms on the First Prize rose.