I guess it all depends on your shooting style, but fast apertures are the main factor to take into account when choosing lenses for most weddings, mainly due to the low light conditions. I shoot with a 50mm F/1.8, 85mm F/1.8, and 35mm F/2 for portraits and candid type shots during the reception and afterwards, and a 12mm f/2 and 50-140 F/2.8 zoom lens during the ceremony. The 12mm covers my wide angle, and the zoom get everything else. (Fuji sells a 50-140, most other companies sell a very similar lens as a 70-200) If I were to pick two lenses for my Canon system, I would probably get a 16-35 f/2.8, and a 70-200 f/2.8 IS. They should get you decent bokeh for portraits, and still be flexible enough to cover most scenarios. I saw that Sigma is making some pretty impressive zoom lenses with 1.8 apertures. That would be like having a bag full of primes in one lens! Pretty affordable too.
