I use a combination of methods, in rough priority:
* Try to work with the sunlight. Finding angles and having people look to the side, shooting into the sun to get flare, rimlight etc....
* Use fill flash on camera. Often -1 to -3 and with gels, ND and 1/4-1 Tungsten filter to go really discreete, as I hate that "flash look".
* Hide in the shadows, but that can easily blow out bright backgrounds, or give a "cold" feeling to the images.
* Use a fill reflector, if I have an assistant with me and take more posed images that gives enough time for this. Most often not for full body shots though I have a very large reflector too, as it can be hard to get close enough to get good effect while not showing the reflector in the full body shots.
* Use a diffusor, same comments as for reflector. Can create some very nice light.
* Have an assistant hold the flash off-camera, using PocketWizard.
* Use a strobist set-up with 1-2 sets of two SB-24 Nikon flashes on a light stand with an umbrella and Pocketwizard. Takes a lot of time to set up, but gives full control and very nice light. Usually there is no time for this on weddings the way I work. If I have to shoot indoors this is a good option.