first of all i just quilted a one block quilt for a woman who found a huge floral print in hawaii and did not want to cut it up... she bordered it beautifully, picking up colors form the print and using tone on tones so they weren't too flat.... then we decided to quilt around the huge flowers and do small leafy vines in between them... we also followed small details inside the large flower centers...
but large florals make great borders, too, just pick up some of the colors and make normal blocks inside, 9 patches, or other simple geometric patterns... this is not the time to make complex stars or floral blocks because they will fight with the border....