Snapshot - all the lenses you've listed so far either fall into the telephoto range if you're using an APS-C camera body (such as the Digital Rebel, XT, 20D, etc.) or are way too slow for much natural light work. For doing weddings, you will definitely want some faster and shorter lenses.
The best single zoom lens that I could recommend - though it isn't inexpensive - is the Canon 24-70mm f/2.8. You could probably shoot a whole wedding and never take that one off the body. It is fast enough for a lot of the natural light situations you'll run into. Its focal length range will handle most, if not all, the situations you'll run into. It's also an extremely well built lens, rugged enough to last you for decades.
In addition, the lens design coupled with the supplied lens hood is by far the best design ever. The lens hood is rather deep. You'd think that it wouldn't work at wide-angle zoom settings. However, the fact is that the lens extends for the wide-angle settings and retracts for the longer settings. Since the hood is mounted to the non-moving lens barrel, this places the front element of the lens only an inch or so behind the front of the hood at 24mm, and about three inches back at 70mm. It will do the absolute best job of protecting the image from stray light and protecting the lens from physical damage of any lens/hood combination on the market.