I always use two 10D with one fitted with 16-35 and the other with 24-70, and bring along the 70-200IS.
16-35 is good for table short and tea-section, 24-70 for general short and 70-200IS for outdoor short.
I use a 24-70 almost exclusively for journalistic weddings and a 19-35 for group shots. A 17-40 would be a good 'do everything' lens, but you won't get the closeup 'in your face' style that a midrange zoom can give.
RuthieBaby: Frankly, I've never come across any church that says no flash, I'm really curious to which ones that do, personally shot in a few, always with flash, even the few I attended, all with flash too.