I do probably 80% of my wedding photos with a fast, normal range zoom (17-50ish on APS, 28-75ish on 35mm). I've been using a Sigma 18-50 f/2.8, a Tamron 28-75 f/2.8, and a Canon L 24-70 f/2.8. The Tamron and Sigma were less than 1/3rd the price of the Canon, but image quality is the same. The build quality of the Tamron and Sigma seems less robust than the Canon.
In addition I find a couple of fast primes, a really wide angle, and a f/2.8 70-200 come in handy.
I have yet to have a digital body fail on me, but I have had almost everything fail: lenses, flash, battery pack, remote triggers, flash cords, flash bracket, etc... Sometimes it was my fault (dropping or forcing something), but most of the time they just stopped working.