Consider putting up curtains or drapes that flow from just above the window all the way to the floor. You can also install a remote control curtain system that will allow you to open the curtains at any time you wish from across the room. This way if the patio is close to the kitchen and you are busy cooking dinner but you wish to have a bit more sunlight in the room, just grab the remote and open the curtains.
You can choose from a wide array of styles and colors that can match the rest of the room or use colors that stand out if you desire. The idea is to help create the atmosphere you desire instead of just having plain huge windows going to the patio.
One great design is to have a valance. You will still be able to open the door or just open the curtain to use the door, but the pretty valance will stay in place giving the door a new look.
You may choose to only use a curtain on the side that does not slide and leave the door completely uncoovered. You may wish to have a sheer curtain behind the main curtain. This way you can leave the sheer over the door except when the door is in use while allowing the sun to filter though into the room. The choices are endless and each one will set the mood for the room while giving those plain patio doors their own personality.