Need a vine for corner of patio
We have a small patio with a lattice top and a post in each corner. One of the corners (faces southwest) has a large mature Bower Vine (Pandorea jasminoides). The post facing northwest has a Solanum jasminoides. The post facing southeast needs a vine -- but which one? Should it balance the size of the Bower Vine, or should it be a smaller size in similar color?
I'd like it to maintain continuity of color with the other vines on this patio and not have thorns. So - a Clematis? Another Solanum jasminoides?
Any ideas? This spot faces southeast with a sunny exposure most of the day. Soil is rich clay with some amendment.