Speaking as a wife, a lot of these pergolas in the pictures are placed right on the patio. Like Aggietaco stated, they are great for vines but you would want big planters oriented to train vines to grow toward the sun. If you are using your patio as outdoor living space and want more protection from the elements then a pergola probably isn't going to make you as happy. Me? I love to grow things so I have morning glories and a hybrid cross vine that are trained to cover our shelter. These die in the winter but during the summer it is a wonderful roof of blooms that the hummingbirds and butterflies love. Our shelter isn't a traditional pergola made of wood but instead an old canopy frame of metal (like the type you see at the big blue box store). When the fabric shade covering wore out we couldn't find a replacement and were going to toss it but instead, it has turned into a backdrop of blooms and hanging baskets.

We have been working on a different part of the landscaping so this is a temporary measure until we can reconstruct the patio and then we will have a regular pergola and some planting beds with more perennial vines or a climbing rose.

Good luck with your roof!