Love these giant bromeliads I was thinking about as features they would definitely add interest but not sure whether they would work in the UK climate. The giant ferns in the background (if that is what they are) also add interest.
Garden bench built into rendered retaining wall. I like the way trees are also in the planter to create two layers, plus a narrow planting at foot of retaining wall and under garden seat. - Gardening And Patio