I would suggest looking into the integrifolia and texensis group of clematis. They aren't clinging like many clems and will be gentle on the shrubbery. There are many colors of blooms to choose from.

I'm adding a link to Clematis on the Web's picture gallery for the integrifolia group. There is also a search feature to look through the different pictures available in other types as well. Just click on the picture search tab and then choose the group you wish to search on the types section.

Tracy

Here is a link that might be useful: Clematis on the Web Integrifolia Pic gallery

I'm in a cooler climate, and my rhodos don't get as large as my family's in PA, but I have Ville de Lyon and Rhapsody growing through one of mine. I would choose ones like these (or integrifolias as suggested) that you trim to the ground each spring so that the growth stays fresh.

I chose these type III's because they grow up into the shrub as the rhodo blooms, then a few weeks later they each have a series of weeks when they bloom, holding their flowers up toward the sun. The effect is that the rhodo is blooming again early and mid summer.