Hi Mick
As promised in chat last night, here are a few suggestions from me. In the largest pot I'd go for either Thunbergia alata 'Susie' (mixture of white yellow and orange flowers) growing up an obelisk or one of the deep purple/black Phormiums. Then I'd use smaller purple/black grasses in the other pots using the same Thunbergia as a trailing plant, space permitting. Not sure how you are going to group seven pots easily though.....
G x